Chemical equation
represents with symbols and formulas the identities and relative molecular or molar amounts of the reactants and products in a chemical reaction
Precipitate
a solid that separates out of a solution during a chemical change
Coefficient
a small whole number that appears in front of a formula in a chemical equation
Word equation
an equation in which the reactants and products in a chemical reaction a represented by words
Formula equation
represents the reactants and products of a chemical reaction by their symbols or formulas
Reversible reaction
chemical reaction in which the products re-form the original reactants
Synthesis reaction
a reaction in which two or more substances combine to form a new compound
Decomposition reaction
a reaction in which a single compound undergoes a reaction that produces two or more simpler substances
Electrolysis
the decomposition of a substance by an electric current
Single-displacement reaction
a reaction in which one element replaces a similar element in a compound
Double-displacement reaction
a reaction in which the ions of two compounds exchange places in an aqueous solution to form two new compounds
Combustion reaction
a reaction in which a substance combines with oxygen, releasing a large amount of energy in the form of light and heat (forms CO2 + H2O)
Composition stoichiometry
deals with the mass relationships of elements in compounds
Reaction stoichiometry
involves the mass relationship between reactants and products in a chemical reaction
Mole ratio
a conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction
Limiting reactant
the substance that controls the quantity of product that can form in a chemical reaction
Excess reactant
the substance that is not used by completely in a reaction
Theoretical yield
the maximum amount of product that can be produced from a given amount of reactant
Actual yield
the measured amount of product obtained from a reaction
Percentage yield
the ratio of the actual yield to the theoretical yield multiplied by 100
Thermochemistry
the study of the transfers of energy as heat that accompany chemical reactions and physical changes
Calorimeter
the measurement of energy absorbed or released as heat in a chemical or physical change
Temperature
a measure of the average kinetic energy of the particles in a sample of matter
Joule
the SI unit of heat, as well as all other forms of energy
Heat
the energy transferred between samples of matter because of a difference in their temperatures
Specific heat
the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree or one Kelvin
Enthalpy change
the amount of energy absorbed by a system as heat during a process at constant pressure (? H) ?H = H of products - H or reactants
Enthalpy of reaction
the quantity of energy transferred as heat during a chemical reaction
Thermochemical equation
an equation that includes the quantity of energy released or absorbed as heat during the reaction as written
Molar enthalpy of formation
the amount of energy as heat resulting from the formation of 1 mol of a substance at constant pressure
Enthalpy of combustion
Tthe enthalpy change that occurs when one mole of a compound is formed from its elements in their state at 25oC and 1 atm
Hess's law
the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process (products - reactants) ?H(products) - ?H (reactants)
Entropy
(S) a measure of the degree of randomness of the particles, such as molecules, in a system
Free energy
(G) the combined enthalpy-entropy function
Free-energy change
(?G) the difference between the change in enthalpy (? H) and the product of the Kelvin temperature and the entropy change T?S at a constant pressure and temperature
activity series
a list of elements organized according to the ease with which the elements undergo certain chemical reactions