Chem Unit 6 - The mole and stoichiometry

Mole

A mole is the chemists unit of measure which indicates a specific quantity of items (In chem these are particles - atoms and molecules) (Since particles are small this is a really big number)

Molar Mass

the mass in grams of a mole of any pure substance

Molar mass of elements

Molar mass is simply the average atomic mass from the periodic table in grams for an element

Molar mass of compounds

For compounds the molar mass is the sum of the molar masses of all the particles in that substance

Percent composition for elements in a compound

Mass of element/Total mass of compound x 100 = % composition

Converting between mass of a sample and moles

To convert between mass and moles,

- divide the given mass by the substances molar mass to find moles

- multiply the given moles by the molar mass to find mass

Stoichiometry

Uses the relationship between the number of particles in a substance in a chemical reaction to make predictions

Mole ratio

The ratio between the coefficients of only two substances in a balanced equation (can be used to predict amounts of reactants or products involved but only when in MOLES)

Yield

the mass of a product from a chemical reaction

Actual yield

the mass of a product produced when a reaction is carried out in a lab

Theoretical yield

the mass of a product predicted to be produced using stochiometry

How can the mass of a product be predicted using tje starting mass of a reactant and stoichiometry?

Convert the given reactant mass to moles using its molar mass, use the balanced equation mole ratio, then convert the moles of the product to grams using molar mass

Equation for percent yield

actual yield/theoretical yield x 100 = % yield

Molarity equation

Molarity= moles solute/liters of solution