reactants
The starting substances in a chemical reaction
products
The ending substances in a chemical reaction
stoichiometry
Quantitative relationships between the amounts of reactants used and the amount of reactants formed by a chemical reaction
mole ratio
Ratio between the numbers of moles of any two substances in a balanced chemical equation
limiting reactants/reagents
Limits the extent of a reaction, determines the amount of product formed
excess reactants/reagents
Reactants leftover when a reaction stops
theoretical yield
Maximum amount of products that can be produced from a given amount of reactants
actual yield
Amount of products produced when a chemical reaction is carried out in an experiment
percent yield
Ratio over actual/theoretical yield as a percent
law of conservation of mass/matter
Matter cannot be created or destroyed, only moved
energy
The ability to do work or produce heat
law of conservation of energy
Energy can be converted from one form to another but not created nor destroyed
chemical potential energy
Energy stored in a substance because of its composition
heat
Energy in the process of flowing from a warmer object to a cooler object
specific heat
Amount of heat required to raise the temperature of one gram of a specific substance by one degree Celsius
calorimeter
Insulated device used for measuring the amount of heat absorbed or released during a chemical or physical process
thermochemistry
Study of heat changes that accompany chemical reactions and phase changes
system
The specific part of the universe that contains the reaction or process you wish to study
surroundings
Everything in the universe other than the system
universe
System plus its surroundings
enthalpy
Heat content of a system at constant pressure
Hess’s law
If you add two plus thermochemical equations to produce the final equation for a reaction, the sum of enthalpy changes for individual reactions is the enthalpy change for the final reaction
spontaneous process
Any physical or chemical change that once begun occurs with no outside intervention
entropy
(S) Measure of the number of possible ways energy in a system can be distributed; chaos
second law of thermodynamics
Spontaneous processes always proceed in a way that the entropy of the universe increases
free energy
Energy that is available to do work
endothermic reaction
Energy is absorbed in a reaction
exothermic reaction
Energy is released in a reaction
reaction rate
Change in concentration of a reactant or product per unit of time mol/Lxs
collision theory
Atoms, ions, and molecules must collide in order to react
activated complex
Temporary, unstable arrangement of atoms in which old bonds are breaking and new bonds are formed
activation energy
Minimum amount of energy that reacting particles must have to form an activated complex
catalyst
A substance that increases the rate of a chemical reaction without being consumed in a reaction
inhibitor
A substance that slows down or inhibits reaction rates
rate law
Relationship between the rate of a chemical equation and concentration of reactants
specific rate constant
K; Relates reaction rate and the concentrations of reactants at a given temperature
reaction order
How rate is affected by the concentration of that reactant
initial rates
R-Instantaneous rate at the start of a reaction
instantaneous rates
R-slope of the straight line tangent to the curve at a specific time
Factors affecting reaction rate
Temperature, surface area, concentration, catalysts/inhibitors
chemical equilibrium
Forward and reverse reactions balance each other as they take place at equal rates
common ion effect
lowering of solubility of a substance because of the presence of a common ion
common ion
Ion that is common to two or more ionic compounds