3.2 Use of amount of substance in relation to masses of pure substances

Question 1

3.2.1 Moles

What is a mole

Answer 1

• The mass of one mole of a substance (in grams) is **equal to its relative formula mass. **

Question 2

3.2.1 Moles

Hoe to work out the number of moles?

Answer 2

Mass/Ar
Mass/Mr

mass - grams

Question 3

3.2.1 Moles

What is the value for Avogadro’s constant?

Answer 3

6.02 x 10^23 per mole.

Question 4

3.2.2 Amounts of substances in equations

Steps to find amounts of substances in equations

Answer 4

1. balance equation
2. find Mr of the known
3. find Mr of unknown
4. calculate moles of known (mass/Mr)
5. find molar ratio between known and unknown
6. calculate moles of unknown
7. find mass of unknown (moles x Mr)