Compounds and Stoichiometry . Flashcards
What are compounds?
They are substances composed of two or more elements in a fixed proportion.
What is molecular weight?
It is the mass (in amu) of the constituent atoms in a compound as indicated by the molecular formula.
what is molar mass?
It is the mass of one mole (avagadro’s) 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; it is related to molarity by multiplying the molarity by the number of equivalents present per mole of a compound.
Equivalents
are moles of the species of interest; are most often in acid-base chemistry (hydrogen ions or hydroxide ions) and oxidation-reduction reactions (moles of electrons or other ions)
What is the law of composition?
states that any pure sample of a compound will contain the same elements in the same mass ratio.
What is empirical formula?
the smallest whole-number ratio of the elements in a compound.
What is the molecular formula?
it either the same as or a multiple of the empirical formula; it gives the exact number of atoms
What is the percent composition?
by mass, determines the mass of the individual element and divide by the molar mass of the compound.
What are combination reactions?
Occur when two or more reactants combine to from one product.
What are decomposition reactions?
occur when one reactant is chemically broken down in two or more products.
What is displacement reactions?
Occurs one or more atoms or ions of one compound are replaced with one or more atoms of ions of anther compound.
Single displacement reactions
occurs when an ion of one compound is replaced with another element.
Combustion reactions?
occur when a fuel and an oxidant (typically oxygen) react, forming the products and water and carbon dioxide.
double displacement reactions
When elements form two different compounds swap places with each other to form two new compounds. Also known as metathesis reaction.
neutralization reactions
are those in which an acid react with a base to form a salt (and usually water)
Balanced equation are determined by using…?
balance the least common atom
balance the more common atoms (usually hydrogen and oxygen.
Balancing the charge, if necessary.
What is the limiting reagent
the reactant that will be consumed first in a chemical reaction.
What is the excess reagent?
the other reactants that are not the limiting.
What is theoretical yield?
The amount of product generated fi all of the limiting reactant is consumed with no side reactions.
What is the actual yield?
typically lower than the theoretical and what actually occurs
What is percent yield?
Calculated by dividing actual yield by theoretical yield and converting into a percentage.
Roman numeral are used in ions to…
represent charge in elements
