Chemistry ch 8,9,16

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