Gen Chem - Compounds and Stoichiometry

Atomic weight

weighted average of the masses of the naturally occurring isotopes of an element

Molecular weight

the sum of the atomic weight of all the atoms in a molecule and its units are atomic mass units (amu) per molecule

Formula weight

sum of the atomic weights of the constituent ions according to its empirical formula (units = amu per molecule)

Equivalent

how many moles of the thing we are interested in will one mole of a given compound produce?

equivalent = mass of compound (g) / gram equivalent weight (g)

Normality

measure of concentration (units = equivalent / L)

Law of constant composition

any pure sample of a given compound will contain the same elements in an identical mass ratio.

Empirical Formula

nearest whole #

Molecular Formula

exact #, a multiple of the empirical formula

Decomposition Rxn

A→ B + C as a result of heating, high-frequency, radiation, or electrolysis

Combination Rxn

A + B → C, 2 or more reactants forming one product

Combustion Rxn

involves hydrocarbon and an oxidant (usually O2)

Single-displacement rxn

atom or ion in a compound is replaced by an atom or ion of another element.

Double-displacement rxn

elements from 2 different compound swap places with each other to form 2 new compounds. occurs when one of the products is removed from the solution as a precipitate or gas or when 2 of the original species combine to form a weak electrolyte.

Neutralization rxn

specific type of double-displacement run where an acid reacts with a base to produce a salt and water.