Moles and Formulas for chemistry

How to find a empirical formula

Use 100g as total if mass not given,

Convert % to mass,

Convert mass to moles,

divide all mole values by the lowest

How to find a Molecular formula

Find empirical formula,

find molar mass of empirical formula,

divide molecular mass by molar mass,

multiply the answer by the empirical formula to get molecular formula.

percent composition

the percent of mass of each element in a compound

Finding Percent Composition

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

molar mass

the total mass in grams of a substance

Unit of molar mass

g/ mol

Particles, atoms, molecules in moles

6.02 X 10^23

Mass, grams in moles

Molar mass of the substance

Volume, Liters, STP in moles

22.4 L

Molarity equation

Molarity = Moles of solute/ liters solution

How to find Molarity

Fill in molarity equation by converting what you can, than convert the answer if needed.

When there is two molarity mentioned use

M1 x V1 = M2 x V2

how many mL are there in 1 L?

1000 mL

To find grams of a element from a compound in percent composition, use

Total given x element mm/ compound mm

In a combustion problem you use

g CO2 × 12.01g/ 44.01g for g carbon and g H2O x 2.02g/ 18.02g for g Hydrogen