Chemistry Notes - Measurement & Calculations Involving The Mole (Page 2 of 3) in pdf

Chemistry Notes - Measurement & Calculations Involving The Mole Page 2

Chemistry Notes

Chapters 5,6 - Measurement & Calculations Involving the Mole

Section 6.1-6.3 - Moles, Molar Mass, Percent Composition and Empirical Formula

Avogadro = Italian scientist and mathematician who calculated the number of particles that make

up a mole of gas must be proportional to its volume

Mole = a unit of measurement in chemistry to represent:

1. (Quantity) Avogadro's Number of particles = 6.022 x 10ˆ23

2. (Mass) Equivalent to 12.0 grams of carbon-12

Molar mass = mass of one mole of a substance; equivalent to the atomic mass unit listed on the

periodic table

Formula mass = sum of all of the atomic mass units of all of the atoms in a chemical compound

Steps -

1. Count up the number of atoms (using the subscripts)

2. Multiply each element by its molar mass

3. Add up all of the molar masses to find the formula mass

Percent composition = percentage by mass of each element in a chemical compound

Steps -

1. Calculate the formula mass (total mass of compound)

2. Divide the individual mass of each element by the total mass of the compound

3. Multiply by 100 to find the percentage

Empirical formula = shows the smallest whole-number ratio of elements in a chemical compound

Steps -

1. Convert the given mass to moles

2. Divide by the smallest number of moles to find the smallest whole-number mole ratio

3. Use the mole ratio numbers as subscripts for the empirical formula

Molecular formula = any whole-number multiple of the empirical formula

Steps -

1. Calculate the empirical formula mass

2. Divide the total molecular formula mass by the empirical formula mass to find the number of

molecules

3. Use the number of molecules as the subscripts for the molecular formula

Mrs. Drurey

- 2 of 3 -

Newton South High School

Chemistry Notes - Measurement & Calculations Involving The Mole Page 2