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is the study of the bulk properties of matter and the conversion of heat into mechanical and/or chemical energy.

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Thermodynamics

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The particular thing or part of the physical universe that we choose to study

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Thermodynamic System

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the real or imaginary separation between the system and the rest of the universe.

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Boundary

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the part of the universe that is outside the system (i.e. everything else)

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Surroundings

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system + surroundings

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Universe

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independent of the size of the system

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intensive variables

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dependent on the size of the system

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extensive variables

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No.

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Can a path variable be considered intensive or extensive?

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when the properties of a system in a certain state are independent of time (stable). At equilibrium, the state variables of a system are not independent. The mathematical relationships among state variables are called "equations of state." Equations of state describe equilibrium conditions.

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Equilibrium

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A collection of gas-phase non-interacting point particles that undergo perfectly elastic collisions. The ideal gas law works very well for gases at high temperatures and low densities (or low pressures). It does not work (at all) for things that are not in the gas phase.

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What is an Ideal Gas?

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The ideal gas law is an equation of state. It describes the mathematical relationship among thermodynamic state variables of a sample of ideal gas at equilibrium. PV = nRT

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Ideal Gas Law

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∆E = q + w q = heat w = work

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The First Law of Thermodynamics

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When heat is added to the system When heat is removed from the system

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When is q positive? Negative?

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When work is done on the system (contraction) When work is done by the system (expansion)

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When is w positive? Negative?

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The value of the state function or variables does not depend on the path taken to reach that specific value.

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State functions (or state variables)

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The value of path variables depends on the path taken to reach that specific value. Work and heat are path variables.

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Path variables (or process variables)

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A characteristic of certain processes in which a system can be restored to its initial state without a net effect in the system or the surroundings.

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Reversible Processes

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Processes in which the system cannot be restored to its initial state without a net effect in the system or the surroundings.

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Irreversible Processes

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0 because V=0

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At constant volume w=?

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measures the amount of heat released, or absorbed, in chemical reactions. Constant volume if bomb calorimeter. Constant pressure if coffee cup calorimeter.

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Calorimeter:

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is the amount of heat (q) required to raise the temperature of an object by one degree. (Extensive state variable)

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Heat Capacity

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H = E + PV Constant pressure. Only changes in volume Enthalpy is a measure of the heat energy that is released or absorbed when bonds are broken or formed during a reaction carried out at a constant pressure.

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What is enthalpy and what conditions does it exist under?

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The total enthalpy of a reaction is independent of the reaction pathway

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Hess's Law:

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T

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For an Ideal gas, what is proportional to E?

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w= -P(V2-V1)

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What does w = at constant pressure

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Endothermic

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If ∆H is positive the reaction is exothermic or endothermic?

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Nothing

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What does enthalpy tell us about spontaneity?

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The randomness of a system. As entropy increases, so does the randomness of the system

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What is entropy? What happens when entropy is high?

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Solid goes to liquid, liquid goes to gas, number of molecules of gas increase in the system.

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When does entropy increase?

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Will continue once started without any external action.

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Spontaneous Process

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will not occur unless an external action is continuously applied.

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Nonspontaneous Process:

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Increasing, can also be zero - then it is in equilibrium.

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The entropy of the universe is always increasing/decreasing?

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a particular set of positions and energies of the individual molecules in a thermodynamic system.

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Microstate (W):

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zero

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In a perfect crystal, entropy is equal to:

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the absolute entropy of 1 mole of substance in its standard state (units J K-1 mol-1) Can use same rules as Hess' law to calculate

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Standard Molar Entropy, S˚

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A state function.

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What kind of function is entropy?

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q(rev) --------- T

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At a constant temperature process what is ∆S equal to

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∆G = ∆H - T∆S At equilibrium is the same without the deltas

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Gibbs free energy equation: (for a constant temp process)

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Spontaneous at constant temp and pressure, where ∆G is negative

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exergonic reaction

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non-spontaneous at content temp and pressure where ∆G is positive

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Endergonic reaction

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Same way as Hess's law!

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How can ∆G˚ be found

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∆G is under special conditions ∆G˚ is under standard state conditions

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What is the difference between ∆G and ∆G˚?

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∆G = ∆G˚ + RTln(Q) At equilibrium ∆G = 0 therefore ∆G˚ = -RTlnK

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What is the relationship between ∆G and ∆G˚?

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Because at equilibrium K=Q

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Why is there only one value of K and a bunch of values of Q

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ratio of products/reactants

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What does K represent

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ln K by 1/T WHERE ln K = (-∆H˚/RT) - (∆S˚/R) You can get this by relating ∆G equations and solving for lnK

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What does van't Hoff Plot relate

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HCl, HNO3, H2SO4, HBr, HI, HClO4, HClO3

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Name the strong acids:

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OH and anything in the first two columns

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What makes something a song base

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pH = pKa + log(base/acid)

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What is the henderson Hasselbalck equation

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the highest energy point of the path in a reaction coordinate diagram going from reactants to products, in either direction.

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Transition State:

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The free energy of the transition state minus the free energy of the reactants.

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Gibbs Free Energy of Activation (∆G‡)

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molecules have enough energy to overcome the forward and reverse energies of activation so equilibrium is established

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Thermodynamically controlled reaction

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The molecules only have enough energy to overcome the forward (or reverse) energies for activation.

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Kinetically controlled reaction

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provides information about the rate of chemical processes and the energy of activation.

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Kinetics

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a detailed description of the steps leading from the reactants to the products of a reaction

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Reaction mechanism:

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- Increase temp - Catalyst - Increase concentration

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What can be modified to increase collision rate?

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An elementary reaction occurs in a single step and passes through a single transition state

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Elementary reaction:

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Describes the overall reaction, but does not detail the individual elementary reaction steps

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Overall reaction:

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The number of reactant molecular entities that are involved in an elementary reaction.

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Molecularity

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the change in concentration of a substance divided by the time interval during which this change is observed.

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Reaction rate

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is an expression for the instantaneous reaction rate in terms of the instantaneous concentration of the species involved in the reaction.

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A rate law

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the rate of a chemical reaction is directly proportional to the molecular concentrations of the reacting substances.

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Law of Mass Action:

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the total number of concentration terms in a rate equation (i.e. sum of all exponents).

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Overall order of a reaction:

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-d[A]/dt

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First oder differential rate law:

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ln[A]ˇt = -kt ln[A]ˇo

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First order integrated rate law

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ln[A] vs time is linear

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How do we know by looking at a graph is something is first order?

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ln(2)/k

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What is the half life of a first order reaction?

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the time required (t1⁄2) for half of the starting material to react

answer

What is half life?

question

-d[A]/dt = k[A]^2

answer

What is the differential rate law of a second order reaction?

question

1/[A]ˇt = kt + 1/[A]ˇo

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What is the integrated rate law for a second order reaction

question

linear plot of 1/[A] vs time

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What graph will show a reaction is second order

question

increase the concentration of one of the two components relative to the other so its concentration appears constant over the course of the reaction. k' = k[B]

answer

Pseudo first order conditions:

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k = Ae^(Ea/RT)

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Arrhenius Equation

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Ea relates to the enthalpy of activation A relates to the entropy of activation

answer

How does Arrhenius differ from Eyring

question

k1k2[E][S]/(k-1 + k2)

answer

Michaelis-Menten Kinetics

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