question

-Kc= concentrations of gases (M) -Kp= as a function of partial pressures of the gases (atmospheres)

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for chemical reactions involving ideal gases, the equilibrium constant K can be expressed either in terms of_(2) (include the type of K used in each case)

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when ∆n=0

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when Kc and Kp are equal?

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-Products formed by the forward reaction may react with each other to regenerate the reactants. -When reactants are mixed, they will begin to react at a forward reaction rate particular to that chemical reaction. - As reactants are depleted and products are formed, however, the rate of the forward reaction begins to slow, and the rate of the reverse reaction begins to increase.

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why reactions may have forward and reverse reactions? what happens to rates?

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-Eventually, the forward and reverse reaction rates will be identical. -reach equillibrium

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what is the ultimate result of the reaction? (think about rates)

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Equilibrium is dynamic, meaning that it is a balance of continuous forward and reverse reactions.

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what is meant when we say equillibrium is dynamic?

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-double-headed arrow aA+bB⇌cC+dD

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To indicate this dynamic nature of equilibrium, chemical equations of reactions with measurable reverse reaction rate are written using a _(symbol and include format of reaction)

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the concentration of reactants and products for a reaction in dynamic equilibrium.

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The equilibrium-constant expression is used to describe_

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For ideal gases and ideal solutions in homogeneous equilibria, where all reactants and products are in the same phase,

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In which two states of the reactants and products in a reaction will the equllibrium expression will be written down directly from the formula? (2)

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equilibrium equation K=([C]^c[D]^d)/([A]^a[B]^b) This expression is called the equilibrium-constant expression.

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For ideal gases and ideal solutions in homogeneous equilibria, where all reactants and products are in the same phase, the extent to which a particular chemical reaction proceeds to products is given by the _(name and formula)

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equillibrium constant

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what K is?

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-K is directly proportional to products -the higher the concentration of products, the larger the value of K will be.

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how K depends on products?

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the stoichimetry coefficients of the the reaction

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what is the source of the powers in the equilibrium-constant expression?

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Greater values of K are associated with reactions running toward completion, whereas smaller values of K are associated with a larger concentration of reactants.

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what large values of K mean? what small values of K mean?

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KK⋘1 reaction favors reactants and lies left K∼1 reaction favors neither reactants nor products and lies center K⋙1reaction favors products and lies right

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what means the following three values of K: (reaction favors_and where lies with respect to reaction) k<<>>1

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Heterogeneous equilibria involve reactants and products that are not all in the same phase.

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what heterongenous equillibria involve?

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-When writing equilibrium-constant expressions for heterogeneous reactions, generally the concentrations of pure solids and liquids are omitted. -Since its concentration isn't changing, the values can usually be excluded.

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When writing equilibrium-constant expressions for heterogeneous reactions, generally the concentrations of _(2) are omitted. why?

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-no - The composition of a pure solid or liquid does not change over the course of the reaction; only its quantity changes. (it does not affect the equillibrium constant but when something like a gas or aquoeous solution changes its mass will change) -can be affected by others but

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because a solid or pure liquid are not included in equillibrium constant expression, does it mean it does not change? explain

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Kc, is calculated using molar concentrations. For gaseous reactions another form of the equilibrium constant, Kp, is calculated from partial pressures instead of concentrations.

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how Kc is calculated by Kp?

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Kp=Kc(RT)^Δn R=0.08206 L⋅atm/(K⋅mol) Temperature is in kelvin

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How Kp and Kc are related? what R value is used in this equation? units of temperature?

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Δn is the change in the number of moles of gas (sum moles products - sum moles reactants).

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how calculate Δn used for the equation that relates Kp and Kc?

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K=K1 X K2 multiply them when a chemical equation is the sum of two chemical equations for which equilibrium constants are already known, the equilibrium constant for the reaction is the product of the equilibrium constants for the individual reactions.

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If the first two equillibrium equations are added together, how get K?

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K will become the inverse Kr=1/K (where Kr is the K for the reverse reaction)

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what happens to K if we reverse the reaction?

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K is raised to that number k^n example: if all reactants and products are multiplied by 2, k^2

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what happens to K when multiply entire equation by a number (n)?

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the equilibrium constant K is defined as the ratio of products to reactants at equilibrium

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at equillibrium, how K is defined?

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products and reactants present

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Because K represents the ratio of products to reactants, the magnitude of K is an indicator of the levels of _ when the reaction is at equilibrium

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their composition does not change throughout the reaction.

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Equilibrium-constant expressions do not include a term for any pure solids or liquids that may be involved since _(reason)

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-they can change in quantity but cannot affect the K - The concentration is effectively equal to 1, and will not impact the magnitude of K.

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what can change about pure solids and liquids? what is the K value for them? what is the consequence of this?

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If the reaction is not at equilibrium, the quantity can still be calculated, but it is called the reaction quotient, Qc, instead of the equilibrium constant, Kc.

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if the reaction is not at equillibrium, what is the name given to the ratio of products and reactants concentrations? include symbol

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When a chemical reaction is at equilibrium, Q (the reaction quotient) is equal to K (the equilibrium constant)

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when a chemical reaction is at equillibrium in terms of Q and K?

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-If a stress is applied to the mixture that changes the value of Q, then the system is no longer at equilibrium. To regain equilibrium, the reaction will either proceed forward or in reverse until Q is equal to K once again. -Alternatively, equilibrium can be disrupted by a change in temperature, which changes the value of K. The result however is the same, and the reaction will proceed forward or in reverse until Q is equal to the new K.

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explain how Le Châtelier's Principle applies to a stress by a change in Q or change in temperature

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If a stress is applied to a reaction mixture at equilibrium, a net reaction occurs in the direction that relieves the stress.

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what Le Châtelier's principle states?

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For an exothermic reaction, a temperature increase causes the value of K to decrease. Then, because Q>K, the reaction shifts toward reactants. The opposite occurs for endothermic reactions.

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For an exothermic reaction and endothermic reactions, how K changes and how this shifts the reaction?

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Chemical reactions can be displaced from their equilibrium positions by changing the concentrations of reactants or products. These changes affect the value of the reaction quotient, Q. The reaction then shifts to increase or decrease Q until it is again equal to the equilibrium constant, K.

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according to Le Châtelier's principle, how concentrations affect the direction of the reaction and Q? when this stops?

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-static equilibrium (state of balance, object is at rest) -dynamic equilibrium (chemistry one)

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what are two types of equilibrium? which one will be used in chemistry?

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-forward process and reverse process take place at the same time so no net change occurs

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dynamic equilibrium

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-the rates of these reactions are equal: Ratef = Rater -Reactants and products continuously "go back and forth over the activation energy hill".

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at equillibrium, how rates of forward and reverse reactions are found? how reactants and products found?

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At Equilibrium, and to remain at equilibrium, neither products nor reactants can escape.

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what needs to be avoided to keep equilibrium? (think about reactants and products)

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-Because the rates are the same, the concentrations of the reactants and products remain constant: -Important distinction: The concentrations of the reactants and product are not necessarily equal

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How concentration of products and reactants are found at equilibrium?

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constant.

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At Equilibrium, a particular ratio of concentrations equals a _

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No, at equllibrium, reaction does not stop, reactants make products and at the same rate the products make reactants (rate of forward reaction=rate of reverse reaction)

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at equilibrium, does it mean the reaction ceased? why?

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-concentration -volume -pressure -temperature

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Le Chatelier's principle predicts how a system at equilibrium would respond to changes in_(4)

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dynamic equilibrium

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chemical reactions are found in which kind of equilibrium?

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-occurs when opposing reactions proceed at equal rates -rate forward=rate reverse -the rate at which the products form from the reactants equals the rate at which the reactants form form the products -concentrations are constant, they cease to change

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chemical equilibrium (what it is and how concentrations found)

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-a mixture of reactants and products whose concentrations cease no longer change with time

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equilibrium state

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closed system

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what kind of system is ideal for a reaction in equilibrium? (think about how maintian it at equilibrium)

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reversible

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to have a reaction to be at equilibrium, it must be_

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-two half arrows pointing in opposing directions ↔

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dynamic equilibrium is represented by writing the equation for the reaction with _

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elementary steps

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the forward reaction and reverse reaction of an equilibrium reaction are called_(think about last chapter)

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the rate law of forward reaction is equal to the rate law of reverse reaction

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at equilibrium, how rate laws are found?

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-k is inversely proportional to Ea. -smaller activation energy, the larger k -the larger k, the faster will the reaction happen

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what is the relation between k and acitvation energy? speed?

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stoichiometry

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rate law of equilibrium reactions is based on_

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-products -the rate laws should be equal, so if Kr is smaller, the concentrations of products should be larger to have it equal

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If Kf>Kr, which must be in greater supply at equillibrium to have this to be true? include what you used to know?

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Keq=[products]^p/[reactants]^r Keq=kf/kr

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what is the equillibrium constant expression?

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-directly from the balanced equation -mechanism.

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Unlike rate laws for overall reactions, the equilibrium constant expression can be written from_ and it is independent of _

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By convention, there are no units for any type of equilibrium constant

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what are the units of Keq? (equillibrium constant)

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k (lower case)=rate constant K (upper case)=equilibrium constant

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how differentiate between rate constant and equilibrum constant?

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Equilibrium will be established regardless of the starting concentrations of reactants or products.

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Equilibrium will be established regardless of _

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-at the point when the two lines (one of reactants and one of products) stop increasing/decreasing and start to be straight lines, at that point equilibrium was reached

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In a graph of concentration vs time, when know we reach equilibrium?

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-no -In every single case, the concentration will change to get to equilibrium equal to K

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after establishing equilibrium, did we end up with same concentrations of products and reactants? why?

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-affect k value, so shift equilibrium and concentrations of products vs reactants will change to reach equilibrium again

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if change temperature, what affect? how fix it?

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Keq

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equilibrium constant symbol?

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Kc=Keq

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constant concentration variable Kc is equal to what?

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Kp=Keq

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constant pressure variable Kp is equal to what?

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Kc will have brackets [A] Kp will use parenthesis and P, (Pa) Never never use brackets with partial pressure!

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which constant you should put brackets: Kc vs Kp? (what you would use for the other?

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rate of the forward and reverse reactions

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Equilibrium occurs when the _ are the same.

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rate forward=rate reverse

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Which quantities are equal in dynamic equilibrium?

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the lines will merge and continue one over the other one

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if have graph of rate vs time, how know when reach equilibrium?

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No, they will not merge because do not have the same concentration. we will have same rates

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at equilibrium, will lines of products and reactants merge?

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a. Keq > 1

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If kf > kr, which of the following is true? a. Keq > 1 b. Keq < 1 c. Keq = 1

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-they no longer change, remain constant -have dynamic equilibrium

answer

at equilibrium, what happens to concentrations of products and reactants?

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no longer change with time

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at equilibrium, the concentrations of reactants and products_

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neither reactants or products can escape form the system

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for equilibrium to occur, _(think in terms of reactants and products)

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-concentrations -equilibrium constant

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at equilibrium, a particular ratio of_equals _

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the rates of forward and reverse reactions

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a. which quantities are equal in dynamic equilibrium?

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when concentrations of reactants and products are no longer changing

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how do we know when equilibrium has been reached in a chemical reaction?

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-the rules by which the equilibrium constant is expressed in terms of the concentrations of reactants and products, in accordance with the balanced chemical equation for the reaction (stoichiometry) -expressed the relationship between the concentrations of reactants and products present at equilibrium

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law of mass action

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products^p/reactants^r -equilibrium-constant expression

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K= (what over what and how this relationship is called)

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-equilibrium constant -numerical value obtained when we substitute molar equilibrium concentrations into equilibrium constant expression

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Kc (name and how obtained)

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-the stoichiometry of the reaction, and not on its mechanism

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the equilibrium-constant expression depends on_and not on its_

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temperature

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Kc is _dependent

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-Use Kc for equilibrium concentrations (in Molarity) -Use Kp for equilibrium partial pressures

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when do you use Kc vs Kp?

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units

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There are no _on Keq

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The magnitude of Keq gives us information on the relative amounts of products and reactants at equilibrium.

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what informaiton Keq give us?

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is a ratio of gaseous product partial pressure(s) to gaseous reactant partial pressure(s) after an equilibrium is established.

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equilibrium constant (Kp)

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-all reactants and products must be in gas phase -if something else is in other phase it will not be included in the equilibrium constant expression

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Kp is only used when_(what needs to be at reaction equation)

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-most of the times they are not -Kp=Kc(RT)^∆n

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Are Kp and Kc equal to each other?

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∆n=moles of gaseous products - moles of gaseous reactants ∆n = (c + d) - (a + b) -look at stoichometric values of reactants and products and use them in formula

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how calculate ∆n?

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-when there is equal number of moles on each side and the change of n will be equal to 0

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When would Kc = Kp ?

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yes they are. -Temperature does not affect this! Only number of moles affect if they are equal or not

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If kc=Kp are equal at 25 degree, are they equal at 100 degree C?

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-Kp when have only gases -Kc apply to all cases (especially aqueous) -Keq apply to all

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Kp will apply when have_, and Kc will apply when have_, and Keq will apply when have_

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-Kc and Kp are basic designations f -The equilibrium constant, Keq, (sometimes referred to simply as K) is calculated in the same way, regardless of what you call it: or Keq specific to the way their concentrations were measured. Keq=products^p/reactants^r

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how Kc and Kp related to Keq?

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temperature

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value of K depends on_

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-it does not depend on starting concentrations equilibrium can be approached from either direction -temperature needs to remain the same to have this statement true

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how does the value of Kc depend on starting concentrations of reactants and products? what can be concluded from this? what needs to remain the same?

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equilibrium-constant expression in terms of partial pressures (Kp)

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when reactants and products in a chemical reaction are gases, we can formulate the_

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units of moles/L (M) are used to calculate Kc; units of partial pressure are used to calculate Kp (atm)

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what is the difference between the equilibrium constant Kc and the equilibrium constant Kp?

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change in number of moles of gas in the balanced chemical equation

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what ∆n is?

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-yes, Kc=Kp when the number of moles of products and the number of moles of gases are equal

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is it possible to have a reaction where Kc=Kp? If so, under what conditions would this relationship hold?

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-equilibrium constants derived from thermodynamics measurements are derived in terms of activities rather than concentrations or partial pressures -the activity of a substance in an ideal mixture is the ratio of concentrations or pressure of the substance either to a reference concentration (1M) or to a reference partial pressure (1atm) -The units of such ratios always cancel and activities do not have units

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why equilibrum constants do not have units?

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-they are equal to 1 always

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what is the equilibrum constant of pure solids and liquids?

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0.00140

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If the concentratio of N2O4 in an equilibrium mixture is 0.00140 M, what is its activity? (assume the solution is ideal)

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the composition of the equilibrium mixture

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the magnitude of the equilibrium constant for a reaction gives us important information about_

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-we have more reactants -reactant side is favored

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If K is less than 1, what it means?

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-we have more products -product side is favored

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If K is more than 1, what it means?

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-equilibrium lies to the right (product side) -favor products

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K>>1 what means?

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-equilibrium lies to the left (reactant side) -favor reactants

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K << 1 what means?

question

products predominate over reactants. If Kc is very large, the reaction is said to proceed to completion.

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If Kc > 10³ (what is favored and direction of reaction)

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appreciable concentrations of both reactants and products are present.

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If Kc is in the range 10⁻³ to 10³ (what is found in this state)

question

reactants predominate over products. If Kc is very small, the reaction proceeds hardly at all.

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If Kc < 10⁻³ (what predominates and direction of reaction)

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-forward and reverse reactions are equal -product and reactant concentrations are not equal

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_are equal and _are not equal at equillibrium

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When the equation for a reversible reaction is written in the opposite direction, the equilibrium constant becomes the reciprocal of the original equilibrium constant. K⁻¹ or K->1/K

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When the equation for a reversible reaction is written in the opposite direction, the equilibrium constant becomes _

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-the square of the original equilibrium constant. (K²) -cubed (K³) -raised to the fourth power (K⁴) -raised to n (K^n)

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When the equation for a reversible reaction is doubled, the equilibrium constant becomes _. if it is tripled, the equilibrium constant becomes_. if multiplied by 4, the equilibrium constant becomes_. if multiplied by n, the equilibrium constant becomes_

question

the product of the original equilibrium constants K=K1*K2

answer

When two equations are added together, the equilibrium constant for the sum of the reactions becomes _

question

K' = 1/K K' = K1* K2 K' = K^2 K' =K^3

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What effect on K will have the following equation manipulations: a. Reverse the reaction b. Add 2 equations c. Double d. Triple

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reciprocal

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the equilibrium-constant expression for a reaction written in one direction is the _of the expression for the reaction written in the reverse direction

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reactants and products are in different phases.

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Heterogenous equilibrium applies to reactions in which _

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The concentration of solids and pure liquids are not included in the expression for the equilibrium constant.

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in heterogeneous equilibrium, what you should take into account? (what is not included)

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-Because they are solid, their concentration change is so little that they are considered to be constant -same applied to liquid

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why solids are not included in the expression for the equilibrium constant? how this applies to liquids?

question

-take into account only gases or aqueous, not solid or liquids -because they are the only ones that are really changing

answer

what two phases you should take into account when writing equilibrium constant expression? why?

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applies to reactions in which all reacting species are in the same phase.

answer

homogeneous equilibrium applies to reactions in which_

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-Even when a solvent is involved in a reaction, we generally exclude it from the equilibrium expression. (like water) -Its concentration is so big that it really does not change as much as the reactants and products of aqueous state do

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what you need to take into account in homogeneous equilibrium, when writing the equilibrium constant expression? (what is not involved) why?

question

- M -M or in atm

answer

The concentrations of the reacting species in the condensed phase are expressed in_. (In the gaseous phase, the concentrations can be expressed in _.)

question

dimensionless

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The equilibrium constant is a _ quantity (think about units)

question

balanced equation and the temperature

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In quoting a value for the equilibrium constant, you must specify the _(2)

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-When the equation for a reversible reaction manipulated, the equilibrium constant changes. -The equilibrium constant changes with temperature.

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why when quoting a value for the equilibrium constant, you must specify the balanced equation and the temperature?

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solvents, solids, and pure liquids

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The concentration of _ (2) are not included in the expression for the equilibrium constant.

question

1. the concentration of a pure solid or liquid has a constant value. If the mass of a solid is doubled, its volume also doubles. Thus, its concentration, which relates to the ratio of the mass to volume, stays the same. Because equilibrium-constant expressions include terms only for reactants and products whose concentrations can change during a chemical reaction, the concentrations of pure solids and pure liquids are omitted 2. what is substituted into the thermodynamic equilibrium expression is the activity of each substance, which is a ratio of the concentration to a reference value. For a pure substance, the reference value is the concentration of the pure substance, so that the activity of any pure solid or liquid is always 1

answer

why pure solids and pure liquids are excluded from equilibrium-constant expressions? [2 explanations]

question

because its concentration is much greater than the concentration of reactants and products

answer

why a solvent is not included in the equilibrium constant expresion?

question

ICE chart

answer

what do you need to use in the case of calculating K when one or more initial (pre-equilibrium) and at least one final (equilibrium) concentration/pressure is known?

question

1. tabulate all the known initial and equilibrium concentrations of the species appear in the equilibrium-constant expression 2. For those species for which initial and equilibrium concentrations are known, calculate the change in concentration that occurs as the system reaches equilibrium 3. Use the stoichiometry of hte reaction (the coefficients in the balanced chemical equation) to calculate the changes in concentration for all other species in the equilibrium-constant expression 4. Use initial concentrations from step 1 and changes in concentration from step 3 to calculate any equilibrium concentrations not tabulated in step 1 5. Determine the value of equilibrium constants

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list steps to follow when calculating K when one or more initial (pre-equilibrium) and at least one final (equilibrium) concentration/pressure is known

question

-indicates the extent at which a reaction proceeds -If K is very large, equilibrium mixture contains mostly substances in the product side. Reaction proceeds far to the right -If k is very small (far less than 1), the equilibrium mixture contains mainly substances on the reactant side.

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What K indicates regarding the reaction? (large vs small)

question

-predict direction in which a reaction mixture achieves equilibrium -calculate equilibrium concentrations of reactants and products

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equilibrium constant allows us to_ (direction of what and calculate what)

question

reaction quotient (Qc) is calculated by substituting the initial (non-equilibrium) concentrations of the reactants and products into the equilibrium constant (Kc) expression

answer

how reaction quotient calculated? (symbol)

question

You will be given the reactant and product initial concentrations in this type of problem.

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In the problem that involves calculating reaction quotient, what will be given to us?

question

-same way that

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The reaction quotient, Qc, is calculated the _ the equilibrium constant, Kc, is calculated

question

-reaction constant is at equillibrium -reaction quotient is not at equilibrium and use values that are not at equilibrium (like initial values)

answer

Reaction quotient (Qc) vs reaction constant(Keq)

question

Qc=Kc

answer

how reaction quotient can tells us that the reaction is at equilibrium?

question

-K the EQUILIBRIUM CONSTANT and is a ratio of EQUILIBRIUM concentrations -The magnitude of the ratio tells us how far toward products the position of equilibrium lies -Q is a REACTION QUOTIENT, and is simply a ratio (or quotient) of NON-EQUILIBRIUM concentrations. -The magnitude only tells the CURRENT ratio of products to reactants

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The difference between Q and K (what it is and what tell us)

question

-Compare the magnitude of Qc to Kc! -The magnitude of the ratio Q is only useful when compared to K. -Depending on how Q relates to K, we can PREDICT the direction the reaction will spontaneously proceed to reach equilibrium.

answer

Suppose you start out with non-zero concentrations of reactants and products in a reaction container. How do we know if the reaction will proceed in the forward direction or the reverse direction?

question

-The system proceeds from left to right to reach equilibrium (toward products) -concentration of products is too small and reactants too large

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If Kc>Qc, direction of reaction and concentrations

question

The system is already at equilibrium

answer

If Kc=Qc, direction of reaction

question

-The system proceeds from right to left to reach equilibrium (toward reactants) -concentration of products too large and reactants too small

answer

If Kc<Qc, direction of reaction and concenttrations

question

This arrow trick only works when K and Q are written in alphabetical order

answer

Arrow trick that tells you the direction of the reaction only works when_ (Q and K)

question

-Initial concentrations, -Changes in concentration (select one of the concentration changes and call it x. Use stoichiometry to determine all the concentration changes in terms of x.), and their -Equilibrium concentrations (calculated from Co and x).

answer

what each letter of the ICE chart will contain?

question

Solve the equation for x, applying any possible simplifications (perfect squares or dropping terms when small), or solve the polynomial.

answer

what are the two ways you can solve the most difficult problems?

question

Check simplifications for validity ( if C is 5% of I, error is tolerable). If not valid, return to step 5 and do not use the simplification.

answer

how check simplification for validity?

question

-Substitute the value of x into the expressions for the equilibrium concentrations and determine their values. -Use the equilibrium concentrations to calculate a K value, and compare it to the given K value to verify the accuracy of the answers.

answer

what is a way to check answer?

question

(X/[A]0)X100% <5%

answer

formula to check if similification is less than 5%

question

nothing, it will still have the same value

answer

what would happen to Q if we change the volume of the container?

question

-look at equilibrium constant exponent (X10^n) and compare it with the lowest initial concentration exponent (X10^n). If their subtraction gives an order of magnitude greater than 3, you can drop the X values because their are negligibles -drop from denominator part

answer

how to determine if we can use the method of dropping terms?

question

(greater X value)/its initial concentration) X 100% If this give you a value less than 5%, you are ok to go! If not, use another method

answer

how to determine if drop method was negligible enough?

question

-If both numerator and denominator are squared (^2) have (square term/square term)

answer

when use the method by perfect squares?

question

when comparing exponent of K and exponent of lowest initial concentration, their subtraction is 3 or less

answer

when use quadratic method instead of dropping?

question

-if a system at equilibrium is disturbed by a change in temperature, pressure, or a component concentration, the system will shift its equilibrium position so as to counteract the effect of the disturbance

answer

what the Le Chatelier's principle states?

question

adjusts in such a way that the stress is offset as the system reaches a "new" equilibrium position

answer

In Le Chatelier's principle, If an external "stress" is applied to a system at equilibrium, the system _

question

1. Changing the concentration of either the reactants or products 2. Changing the pressure or volume (applies to gas reactions only). 3. Changing the reaction temperature (only one that affects K)

answer

There are 3 external stresses or factors we'll look at as they apply to Le Châtelier's Principle:(include which of these affects K)

question

-concentration, pressure, or temperature -shift its equillibrium position as to counter the effect of the disturbance

answer

if a system is disturbed by a change in _(3), the system will_

question

adding or removing a reactant or product

answer

concentration can be changed by_(2)

question

-if a substance is added to a system at equillibrium, the system reacts to consume some of the substance if a substance is removed from a system, the system reacts to produce more of a substance

answer

explain how equillibrium is shifted by concentration (add vs remove)

question

-changing the pressure by changing volume

answer

how pressure can affect the equillibrium?

question

-At a constant temperature, reducing the volume of a gaseous equilibrium mixture causes the system to shift in the direction that reduces the number of moles of gas -go to side that has less moles

answer

explain how equilibrium is affected by a change in pressure (if pressure increases)

question

-if the temperature of a system at equilibrium is increased, the system reacts as if we added a reactant to an endothermic reaction or a product to an exothermic reaction. -the equilibrium shifts in the direction that consumes the excess of reactant namely heat

answer

explain how increase in temperature affects equilibrium

question

a. increase temperature=reaction shifts right (toward products) b. decrease temperature=reaction shifts left (toward reactants) -heat would be treat it as a reactant

answer

in an endothermic reaction, how equilibrium shifts if: (explain how heat would be treated) a. increase temperature b. decrease temperature

question

a. increase temperature, reaction shifts left (toward reactants) b. decrease temperature, reaction shifts right (toward products)

answer

in an exothermic reaction, how equilibrium shifts if: (explain how heat would be treated) a. increase temperature b. decrease temperature

question

-chances of collision increased, increased pressure. -Increase volume, slow things down so have less pressure

answer

what happens if we have smaller volume? increase volume?

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-it means that the reactant and product concentrations change over time to accommodate the new situation -shift does not mean that the equilibrium constant is altered; the equilibrium constant remains the same (as long the temperature remains the same)

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What shift means when we say equilibrium shifts until a new state of balance s attained? how this affects equilibrium constant?

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minimizes or reduces the effect of the change

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le chatelier principle states that the change is in the direction that_

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-if a chemical system is already at equilibrium and the concentration of any substance in the mixture is increased (either reactant or product), the system reacts to consume some of that substance -Conversely, if the concentration of a substance is decreased, the system reacts to produce some of that substance

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how le chatelier principle applies to changes in concentration?

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no

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does changing the concentration of reactant or product affect the equilibrium constant (K)?

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-Adding/removing a pure solid or liquid in a heterogeneous equilibrium reaction will not cause a shift in the reaction, i.e., Le Chatelier's Principle does not apply. -however, it can change if something else changes (its mass can change)

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Explain what adding/removing a pure solid or liquid in a heterogeneous equilibrium reaction will cause

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[D] will decrease because it will react with C to reduce it and produce more A and B

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A+B↔C +D If we increase [C], how affect [D]?

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-nothing will happen because A is a solid

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A(s)+B(g)↔C(s) +D(g) If we increase [A], how equillibrium shift?

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-it will shift to the left and increase the concentration of A

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A(s)+B(g)↔C(s) +D(g) If we increase [D], how equillibrium shift and how affect A?

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-increase mass (be affected by other that are not solid or liquid) -cannot affect others by changing itself -if increase/decrease concentration, will not affect equilibrium. If others (like gases or aqueous) concentration changes, it can be affected (the mass of solid change)

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a pure solid or liquid can _but cannot _(in changes in equilibrium)

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-volume is decreased thereby increasing its total pressure, le chatelier's principle indicates that the system responds by shifting its equilibrium position to reduce the pressure -a system can reduce its pressure by reducing the total number of gas molecules (fewer molecules of gas exert lower pressure). Thus, the equilibrium shifts to the side of the reaction that has less number of moles -at a constant tempreature, reducing the volume of a gaseous equilibrium mixture causes the system to shift in the direction that reduces the number of moles of gas

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what happens if volume is decreased? (use le chatelier's principle)

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-volume is increased thereby decreasing its total pressure, le chatelier's principle indicates that the system responds by shifting its equilibrium position to increase the pressure -a system can increase its pressure by increasing the total number of gas molecules (more molecules of gas exert lower pressure). Thus, the equilibrium shifts to the side of the reaction that has more number of moles -at a constant tempreature, increasing the volume of a gaseous equilibrium mixture causes the system to shift in the direction that produces more gas molecules

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what increasing the volume causes?

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a. decrease volume= increase pressure, shift toward products or B side, new equilibrium favors products to reduce total moles of gas [shift to this side because has 1 mol, which is less than 2 mol of A] b. increase volume= decrease pressure, shift toward reactants or 2A side, new equilibrium favors reactants to increase total moles of gas [shift to this side because has 2 mol, which is more than 1 mol of B]

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2A(g)↔B(g) what happens if: (how affect pressure, shift of equilibrium, number of moles of gas) a. decrease volume b. increase volume

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-It will shift to the left, the side with a larger number of moles of gas

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what happens to equilibrium 2SO2(g)+O2(g)↔2SO3(g), if the volume of the system is increased?

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when number of moles in reactants is equal to number of moles in products ex: H2+I2↔2HI [2:2 ratio]

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in which case changing the pressure does not influence the equilibrium position?

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No they alter partial pressures of the gaseous substances

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does pressure-volume changes affect value of K? what they alter?

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-pressure increases if additional amounts of any reacting components are added to the system -total pressure in the reaction may increase by adding a gas that is not involved in the equilibrium, which would not shift the equilibrium but only the pressure

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how can we change pressure without changing volume?

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not affect reaction!

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Increasing pressure by injecting an inert gas will _reaction (how affect it)

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A temperature change will cause a reaction shift AND an increase or decrease in the equilibrium constant

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what a change of temperature would cause? (2)

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Imagine that heat is either a reactant or product.

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how to deal problems that have increasing/decreasing temperature?

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If temperature is increased, it is increased for the entire equilibrium mixture. The reaction will shift in such a way as to remove some of the added heat.

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if temperature is increased, what happens in terms of le chatellier principle?

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If temperature is reduced, it is decreased for the entire equilibrium mixture. The reaction will shift in a way to replace some of the heat that was removed.

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if temperature is decreased, what happens in terms of le chatellier principle?

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The best way to remember how a temperature change affects an equilibrium reaction is to think of heat as a reactant (endothermic) or product (exothermic).

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The best way to remember how a temperature change affects an equilibrium reaction is to think of heat as a _(as what and exothermic vs endothermic)

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a. negative -∆H b. treat heat as product c. add heat: shift left and K decreases d. remove heat: shift right and increase K

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exothermic: a. sign of ∆H b. heat where found in reaction c. what happens when add heat? (shift and K effect) d. what happen when remove heat?(shift and K effect)

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a. positive +∆H b. treat heat as reactant c. add heat: shift right and increase K d. remove heat: shift left and decrease K

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endothermic reaction: a. sign of ∆H b. heat where found in reaction c. what happens when add heat? (shift and K effect) d. what happen when remove heat?(shift and K effect)

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nothing, Keq will remain the same because it is only affected by temperature

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A+C↔D+F what will happen to Keq if we decrease the concentration of F?

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-Keq will increase -equillibrium will shift to products, more products, Keq is directly proportional to products, Keq will increase

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what will happen to Keq, in an exothermic reaction, if heat decreases? why?

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as temperature increases, a larger fraction of molecules in the liquid phase have enough energy to overcome their inter molecular attractions and go into the vapor; the evaporation process is endothermic. Raising the temperature of an endothermic reaction shifts the equilibrium to the right, increasing the amount of gas present

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use Le CHatelier's principle to explain why the equilibrium vapor pressure of a liquid increases with increasing temperature

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-absorbed -the right, in the direction of making more products, and K increases

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in an endothermic reaction, heat is _as reactants are converted into products , shifting the equilibrium to_. how affects K?

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-produced -converted into products -to left -in the direction of making more reactants, and K decreases

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in an exothermic reaction, heat is_as reactants are converted into products, shifting the equilibrium to_. how affects K?

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a. endothermic: increasing temperature results in higher K value b. exothermic: increasing temperature results in lower K value

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how increasing T in the following types of reactions affect K: a. endothermic b. exothermic

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as we lower the temperature, the equilibrium is shifted in the direction that produces more heat

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what effect cooling has on a reaction?

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a. endothermic: shifts the equilibrium to left, decreasing K b. exothermic: shifts the equilibrium to the right, increasing K

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how cooling would affect: (shift and K value) a. endothermic b, exothermic

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-does not cause a shift in the equilibrium reaction -does not change K -HOWEVER, the system will reach equilibrium sooner -A catalyst lowers Ea for both forward and reverse reactions and therefore increases the rates of both the forward and reverse reactions

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how adding a catalyst affects? (equilibrium shift, K, what else?) why?

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-increases the rate at which equilibrium is reached -overall composition of the mixture at equilibrium.

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A catalyst _ but does not change the _

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a. the energy difference between the initial state and the transition state

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what quantity affects the speed of the reaction: a. the energy difference between the initial state and the transition state or b. the energy difference between the initial state and the final state?

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No, the presence of a catalyst can accelerate the reaction but does not alter the value of K, which is what limits the amount of product produced

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can a catalyst be used to increase the amount of product produced for a reaction that reaches equilibrium quickly in the absence of a catalyst?

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left

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what direction of shift would be seen if Increase product(s) Decrease reactant(s)?

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right

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what direction of shift would be seen if Decrease product(s) Increase reactant(s)?

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no shift

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what direction of shift would be seen if Increase/Decrease mass of pure solid or liquid reactant(s)/product(s)?

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Favors inc. in mol of gas

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what direction of shift would be seen if Increase container volume?

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Favors dec. in mol of gas

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what direction of shift would be seen if Decrease container volume?

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Favors shift for removal of heat

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what direction of shift would be seen if Increase rxn temp?

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Favors shift for production of heat

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what direction of shift would be seen if Decrease rxn temp?

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no shift

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what direction of shift would be seen if catalyst is added?

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a. yes and no b. yes and no c. yes and yes d. no and no

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shift reaction? shift equillibrium constant? a. concentration b. pressure (volume) c. temperature d. catalyst

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volume

answer

pressure-_ has to work hand in hand when discussing equilibrium.

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