Chemistry Math Reference Sheet (Page 2 of 3) in pdf

Chemistry Math Reference Sheet Page 2

• % Composition:

o Steps:

1. Find molar mass of each element (parts)

2. Find the total molar mass of the compound (whole)

Part

X 100

Whole

• Empirical Formula (E.F.):

o Steps:

1. The amount of each element should be listed in grams. If analysis of the

compound is in percent, convert to grams: assume a 100 g sample of the

compound.

2. Convert grams of EACH element to moles (T-chart).

3. Divide moles of each element by the smallest number of moles.

4. Round each answer from “3” to the nearest whole number and write the

empirical formula using these numbers as subscripts.

• Molecular Formula:

o Steps:

1. If it is not given, determine the empirical formula of the compound. (Follow all

steps necessary to determine an empirical formula)

2. Calculate molar mass of the empirical formula.

3. Divide the molar mass of the molecular compound by the molar mass of the

empirical formula.

4. Round the answer to “3” to the nearest whole number and multiply all

subscripts in the empirical formula by this number.

• Stoichiometry:

o Steps:

1. Write the balanced equation

2. What do you know? What are you looking for? SET UP YOUR PROBLEM!

3. Make a T-chart being sure that UNITS CANCEL OUT. Always start the T-chart

with your given information!

MASS-MASS Relationship: (given moles) (mole ratio) (unknown

MASS-MOLE Relationship: (given moles) (mole ratio)

Chemistry Math Reference Sheet Page 2