General Chemistry Ch 4. Compounds and Stoichiometry Flashcards
Compounds
Substances composed of two or more elements in a fixed proportion
Molecular weight
The mass (in amu) of the constituent atoms in a compound as indicated by the molecular formula
Molar mass
The mass of one mole of a compound, usually measured in grams per mole
Gram equivalent weight
A measure of the mass of a substance that can donate one equivalent of the species of interest
Normality
The ratio of equivalents per liter, related to molarity by multiplying the molarity by the number of equivalents present per mole of compound
Molarity
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Equivalents
Moles of the species of interest, equivalents are most often seen in acid-base chemistry and oxidation reduction reactions
Law of constant composition
States that any pure sample of a compound will contain the same elements in the same mass ratio
Empirical formula
The smallest whole number ratio of the elements in a compound
Molecular formula
Either the same as or a multiple of the empirical formula, gives the exact number of atoms of each element in a compound
Percent composition of mass
Divide the mass of the individual element by the molar mass of the compound
Combination reactions
When two or more reactants combine to form one product
Decomposition reactions
When one reactant is chemically broken down into two or more products
Combustion reactions
Occur when a fuel and an oxidant react, forming the products water and carbon dioxide
Displacement reactions
When one or more atoms or ions of one compound are replaced with one or more atoms or ions of another compound
Single-displacement reactions
Occur when an ion of one compound is replaced with another element
Double-displacement reactions
Occur when elements from two different compounds trade places with each other to form two new compounds
Neutralization reactions
Those in which an acid reacts with a base to form a salt (and usually water)
Balanced equations determination steps
- Balancing the least common atoms
- Balancing the more common atoms (H and O)
- Balancing charges if necessary
Limiting reagent
The reactant that will be consumed first in a chemical reaction
Excess reagents
Reactants that are not consumed first in a chemical reaction
Theoretical yield
The amount of product generated if all of the limiting reactant is consumed with no side reactions
Actual yield
Typically lower than the theoretical yield
Percent yield
Actual yield divided by theoretical yield and converting to a percentage
Roman numerals ions
Used for non representative elements to donate ionic charge
-ous ending
Used to indicate lesser charge
-ic ending
Used to indicate greater charge
-ide ending
End all monatomic anions
Oxyanion suffixes
Indicate how oxidized the central atom is, those with a lesser amount of oxygen are given the suffix -ite and those with a greater amount are given the suffix -ate
Oxyanion prefixes
For oxyanion series with more than two members, the species with the fewest oxygens is given the prefix hypo- and the species with the most oxygens is given the prefix per-
Polyatomic ions containing hydrogen
Denote the number of hydrogens using hydrogen to denote one or dihydrogen to denote two
Ionic charges
Predictable by group number and type of element (metal or nonmetal) for representative elements, but are generally unpredictable for non representative elements
Metal ionic charge
Form positively charged cations based on group number
Nonmetal ionic charge
From negatively charged anions based on the number of electron needed to achieve an octet
Electrolytes
Contain equivalents of ions from molecules that dissociate in solution, the strength of an electrolyte depends on its degree of dissociation or salvation
