Stoichiometry Notes Chem

Stochiometry

Study of quantitative relationships between the amounts of reactants used and amounts of product formed by a chemical reaction

Mole ratio

Ratio between the numbers of moles of any two substances in a balanced chemical equation

Coefficients indicate...

Relationships between moles of reactants and products

Mole-mole problems

Conversion between moles of one substance to moles of another

Mole-mole step 1

Write balanced equation (if not given)

Mole-mole step 2

Convert the number of moles of the given to the number of moles of the unknown using dimensional analysis

Mass-mass problems

Stoichiometric problem in which the mass of one substance is determined from the mass of another substance involved in the same reaction

Mass-mass step 1

Write the balanced equation

Mass-mass step 2

Convert given mass to moles using molar mass of given

Mass-mass step 3

Convert moles of given to moles of unknown using molar ratio

Mass-mass step 4

Convert moles of unknown to mass of unknown using molar mass of unknown

Mass-volume problems

The volume of one substance is determined from the mass of another substance in the reaction

Mass-volume step 1

Write the balanced equation

Mass-volume step 2

Convert given mass to moles using molar mass of given

Mass-volume step 3

Convert moles of given to moles of unknown using molar ratio

Mass-volume step 4

Convert moles of unknown to volume of unknown using molar volume (molar volume = 22.4 L)

Volume-volume problems

Same as mole-mole, coefficients represent ratio of volumes of gases involved in equation

The amount of products formed is...

Dependent on the amounts of reactants available

Excess reactant

The substance that is not completely used up, there is more than what is needed

Limiting reactant

The reactant that controls how much product we get

Finding limiting reactant step 1

Write the balanced equation

Finding limiting reactant step 2

Choose one of the products as your unknown (doesn't matter which)

Finding limiting reactant step 3

Convert each reactant mass to the mass of your chosen product using the mass-mass products

Finding limiting reactant step 4

The reactant that produces the smaller amount of product is the limiting reactant

Percent yield

Percent of the expected yield that is actually obtained

Percent yield formula

actual yield/theoretical yield x 100

Expected yield

Amount of product that should be produced based on calculations

Actual yield

Amount of product that is actually produced from a chemical reaction