Honors Chemistry Final Exam Study Guide – Flashcards
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Mole
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SI unit for measuring the amount of substance;
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Molar Mass
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the mass of a mole of an element
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Representative particles
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refers to the species present in a substance: usually atoms, molecules, or formula units
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Avogadro's number
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the number of representative particles in a mole
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Avogadro's hypothesis
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states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles
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Molar volume
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the quantity, 22.4 L
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Dimensional analysis
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mole to mass, mole to volume
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Percent Composition
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percent by mass of each element in the compound by which the relative amounts of the elements in a compound are expressed
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STP (Standard Temperature and Pressure)
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a temperature of 0˚C and a pressure of 101.3 kPa, or 1 atmosphere (atm)
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Empirical formula
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the basic ratio gives the lowest whole-number ratio of the atoms of the elements contained in the compound
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Molecular formula
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either the same as its experimentally determined empirical formula, or it is a simple whole-number multiple of its empirical formual
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Types of reactions
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the five general types of reaction are combination, decomposition, single-replacement, double-replacement, and combustion
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Single replacement
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a chemical change in which one element replaces a second element in a compound
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Double replacement
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a chemical change involving an exchange of positive ions between two compounds
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Combination
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a chemical change in which two or more substances react to form a single new substance
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Decomposition
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a chemical change in which a single compound breaks down into two or more simpler products
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Combustion
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a chemical change in which a single compound breaks down into two or more simpler products
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Predicting products
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the number of elements and/or compounds reacting is a good indicator of possible reaction type and thus possible products
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Stoichiometry
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the calculation of quantities in chemical reactions; subject of chemistry
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Limiting Reactants
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the regent that determines the amount of product that can be formed by a reaction
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Excess reactants
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the reactant that is not completely used up in a reaction
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Actual yield
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the amount of product that actually forms when the reaction is carried out in the laboratory
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Theoretical yield
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the maximum amount of product that could be formed from given amounts of reactants
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Percent yield
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the ration of the actual yield to the theoretical yield expressed as a percent.
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Mole ratios
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a conversion factor derived from the coefficients of a balanced chemical equation interpreted in terms of moles
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Gases
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- the particles in a gas are considered to be small, hard spheres with an insignificant volume. - the motion of the particles in a gas is rapid, constant, and random. -All collisions between paricles in a gas are perfectly elastic
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Liquids
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- the interplay between the disruptive motions of particles in a liquid and the attractions among the particles determines the physical properties of liquids
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Solids
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- the general properties of solids reflect the orderly arrangement of their particles and their fixed locations of their particles
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Kinetic energy
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the energy an object has because of its motion
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Kinetic theory
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all matter consists of tiny particles that are in constant motion
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Phase changes
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the conditions of pressure and temperature at which two pahses exist in equilibrium are indicated on a phase diagram by a line separating the phases
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Elastic collisions
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kinetic energy is transferred without loss from one particle ot another, and the total kinetic energy remains constant
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melting point
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the temperature at which a solid changes into a liquid
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boiling point
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the temperature at which the vapor pressure of the liquid is just equial to the external pressure on the liquid - When a liquid is heated to a temperature at which particles throughout the liquid have enough kinetic energy to vaporize, the liquid begins to boil
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normal boiling point
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the boiling point of a liquid at a pressure of 101.3 kPa
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Freezing point
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the temperature at which a liquid changes into a solid
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Kelvin scale
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- the kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles of the substance
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Crystal
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the particles are arranged in an orderly, repeating, three-dimensional pattern called a crystal lattice - the shape of a crystal reflects the arrangement of the particles within the solid.
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Unit Cell
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the smallest group of particles within a crystal that retains the geometric shape of the crystal
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Atmospheric pressure
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results from the collision of atoms and molecules in air with objects - decreases as you climb a mountain because the density of the Earth's atmosphere decreases as the elevation increases
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Dynamic equilibrium
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- in a system at constant vapor pressure, a dynamic equilibrium because the rate of evaporation of liquid equals the rate of condensation of vapor
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vapor pressure
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measure of the force exerted by a gas above a liquid
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alloropes
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two or more different molecular forms of the same element in the same physical state
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Boyle's Law
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pressure and volume - if the temperature is constant, as the pressure of a gas increases, the volume decreases - Boyle's law states that for a given mass of gas at constant temperature, the volujme of the gas varies inversely with pressure
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Dalton's Law of partial pressure
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-in a mixture of gases, the total pressure is the sum of the partial pressures of the gases - Dalton's law of partial pressure states that, at a constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases.
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Ideal Law
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- to calculate the number of moles of a contained gas requires an expression that contains the variable n - The combined gas law can be modified to include the number of moles
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Combined Law
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-describes the relationship among the pressure, temperature, and volume of an enclosed gas - the combined gas law allows you to do calculations for situations in which only the amount of gas is constant
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Charles's Law
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temperature and volume - as the temperature of an enclosed gas increases, the volume increases, if the pressure is constant - Chales's law states that the volume of a fixed mass of gas is directly proportional to its Kelvin temperature if the pressure is kept constant
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Gay-Lussac's Law
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pressure and temperature - as the temperature of an enclosed gas increases, the pressure increases, if the volume is constant - Gay-Lussac's law states that the pressure of a gas is directly proportional to the Kelvin temperature if the volume remains constant
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Properties of water
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- Many unique and important properties of water - including its high surface tension and low vapor pressure - result from hydrogen bonding - the structure of ice is a regular open framework of water molecules arranged like a honeycomb
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surface tension
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the inward force, or pull, that tends to minimize the surface area of a liquid
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solute
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the dissolving medium in a solution
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solvent
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the dissolving particles in a solution - A solvent dissolves the solute. The solute becomes dispersed in the solvent.
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Solvation
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the process by which the positive and negative ions of an ionic solid become surrounded by solvent molecules
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Electrolytes
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a compound that conducts an electric current when it is in an aqueous solution or in the molten state. - all ionic compounds are electrolytes because they dissociate into ions.
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Nonelectrolytes
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a compound that does not conduct an electric current in either aqueous solutions or in the molten state
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Aqueous solution
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water that contains dissolved substances
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Molarity (M)
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the number of moles of solute dissolved in one liter of solution
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Molality (m)
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the number of moles of solute dissolved in 1 kilogram (1000g) of solvent. - the unit molality and mole fractions are two additional ways in which chemists express the concentration of a solution
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Mole fraction
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The ratio of moles of that solute to the total number of moles of solvent and solute
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Vapor pressure reduction
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- colligative property - the decrease in a solution's vapor pressure is proportional to the number of particles the solute makes in solution
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freezing point depression
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-colligative property -the difference in temperature between the freezing point of a solution and the freezing point to the pure solvent - The magnitude of the freezing point depression is proportional to the number of solute particles dissolved in the solvent and odes not depend upon their identity
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boiling point elevation
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- colligative property - the difference in temperature between the boiling point of a solution and the boiling point of the pure solvent - The magnitude of the boiling point elevation is proportional to the number of solute particles dissolved in the solvent
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solubility
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the amount of solute that dissolves in a given quantity of a solvent at a specified temperature and pressure to produce a saturated solution -solubility is often expressed in grams of solute per 100g of solvent
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concentration
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measure of the amount of solute that is dissolved in a given quantity of solvent
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Heat (q)
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energy that transfers from one object to another becasue of a temperature difference between them -heat always flows from a warmer object to a cooler object
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heat of reaction
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the enthalpy change for the chemical equation exactly as it is written
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heat of condensation
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amount of heat released when one mole of vapor condenses at the normal boiling point
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endothermic
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process that absorbs heat from the surroundings - in an endothermic process, the system gains heat as the surroundings cool down
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heat capactiy
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the amount of heat needed to increase the temperature of an object exactly 1˚C -the heat capacity of an object depends on both its mass and its chemical composition.
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heat of fusion
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heat absorbed by one mole of a solid substance as it melts to a liquid at a constant temperature
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heat of solidification
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the heat lost when one mole of a liquid solidifies at a constant temperature
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exothermic
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process that releases heat to its surroundings - In an exothermic process, the system loses heat as the surroundings heat up
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joule
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SI unit of energy; 1 joule of heat raises the temperature of 1g of pure water 0.2390˚C
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1J
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=.2390cal
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4.184J
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= 1 cal
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Hess's Law of Heat Summation
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if you add two or more thermochemical equations to give a final equation, then you can also add the heats of reaction to give the final heat of reaction. - Hess's law allows you to determine the heat of reaction indirectly
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Heat of vaporization
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amount of heat necessary to vaporize one mole of a given liquid
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specific heat
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the amount of heat it takes to raise the temperature of 1g of the substance 1˚C
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calorie (cal)
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the quantity of heat needed to raise the temperature of 1g of pure water 1˚C
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Enthalpy (H)
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the heat content of a system at a constant pressure
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calorimetry
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the precise measurement of the heat flow into or out of a system for chemical and physical processes - In calorimetry, the heat released by the system is equal to the heat absorbed by its surroundings. Conversely, the heat absorbed by a system is equal to the heat released by its surroundings
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Chemical equilibrium
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a state of balance reached by a reaction
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equilibrium expression
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an expression at equilibrium
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Le Chatelier's Principle
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If a stress is applied to a system in dynamic equilibrium, the system changes in a way that relieves the stress
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equilibrium position
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indicates whether the reactants or products are favored in a reversible reaction
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Equilibrium constant
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the ratio of product concentrations to reactant concentrations at equilibrium
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factors affect equilibrium
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stresses that upset equilibrium of a chemical system include: changes in the concentration of reactants or products, changes in temperature, and changes in pressure.
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Arrhenius definitions
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Arrhenius said that acids are hydrogen-containg compounds that ionize to yield hydrogen ions in aqueous solution. He also said that bases are compounds that ionize to yield hydroxide ions
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Bronsted-Lowery definitions
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the Bronsted-Lowery theory defines an acid as a hydrogen-ion donor, and a base as a hydrogen-ion acceptor.
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Lewis definitions
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Lewis proposed that an acid accepts a pair of electrons during a reaction, while a base donates a pair of electrons
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Lewis acid
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substance that can accept a pair of electrons to form a covalent bond
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Lewis base
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substance that can donate a pair of electrons to form a covalent bond
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Acid dissociation
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the ratio of the concentration of the dissociated form of an acid to the concentration of the undissociated
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monoprotic
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acids that contain one ionizable hydrogen
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diprotic
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acids that contain two ionizable hydrogens
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triprotic
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aacids taht contain three ionizable hydrogens
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conjugate acids
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particle formed when a base gains a hydrogen
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conjugate base
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particle that remains when an acid has donated a hydrogen ion
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self ionization
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reaction in which water molecules produce ions
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base dissociation
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the ratio of the concentration of the conjugate acid times the concentration of the hydroxide ion to the concentration of the base
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amphoteric
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substance that can act as both an acid and a base is said to be amphoteric
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pH
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negative logarithm of the hydrogen-ion concentration
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strong acids
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completely ionize in aqueous solution (hydrochloric acid and sulfuric acid)
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weak acids
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ionized only slightly in aqueous solution (acetic acid)
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strong bases
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dissociate completely into metal ions and hydroxide ions in aqueous solution (calcium hydroxide, magnesium hydroxide)
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weak bases
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react with water to form the hydroxide ion and the conjugate acid of the base (ammonia)
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oxidation-reduction reactions (Redox reactions)
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-The substance gaining oxygen is oxidized, while the substance losing oxygen is reduced
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oxidation
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complete or partial loss of electrons or gain of oxygen
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reduction
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complete or partial gain of electrons or loss of oxygen
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reducing agent
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substance that loses electrons
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oxidizing agent
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substance that accepts electrons
