12 terms

MCAT GenChem - Compounds & Stoichiometry

Compounds & Stoichiometry
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Avogadro's Number
1 mole = 6.02 x 10²³ atoms
gram equivalent weight
gram equivalent weight = molar mass/n

n - number of protons, hydroxide ions, electrons, or monovalent ions produced by whatever compound is used

ie - One mole of HCl will donate 1 mole of H+ ions. Divide the molar mass of HCl by the number of protons consumed per particle (1 proton donated) and you'll get the gram equivalent weight.
Normality
number of equivalents of a solute/ liter of solution
(6M HCL = 6N; 6M H2SO4 = 12N --> 12 moles H+/ L sol'n)
Law of Constant Composition
a given compound ALWAYS has the same composition, regardless of where it comes from.
Ex. Water always contains 2 H atoms per O atom.
Empirical Formula
a formula showing the lowest whole number ratio of atoms in a compound. To calculate, find the mole ratio of the atoms(every atom divided by lowest mole quantity) assuming a 100 g sample.
Molecular Formula
the exact formula of a molecule, giving the types of atoms and the number of each type (not always the simplest formula; can be some multiple of the simplest)
Combination Reaction
A + B --> C
A reaction in which two or more substances combine to form a single substance.
Decomposition Reaction
A --> B + C
A reaction in which a single compound breaks down to form two or more simpler substances.
Single Displacement Reaction
a reaction in which atoms of one element take the place of atoms of another element in a compound; e.g. redox reactions.
Double Displacement Reaction
a reaction in which a gas, a solid precipitate, or a molecular compound forms from the apparent exchange of atoms or ions between two compounds.
Neutralization Reaction
Double displacement reaction in which an acid and a base mix to form water and a salt.
Percent Yield
% yield = actual yield/theoretical yield x 100