1. The Mole Learning Objectives: Explain the terms amount of substance, mole and the Avogadro constant. Define and use the term molar mass. Carry out calculations involving masses using the amount of substance in moles.

2. Introduction The Avogadro constant, N A, is the number of atoms per mole of the carbon-12 isotope –N A = 6.02 x 10 23 mol -1 A mole is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope

4. Working out the masses You find the mass of 1 mole of a substance in the following way: Work out the relative formula mass, and attach the units ‘grams’ e.g. One mole of H atoms has a mass of 1.0g One mole of Pb atoms has a mass of 207.2g

5. More examples: 1 mole of oxygen gas (O 2 ) = 32g (2x16) You should ALWAYS state the chemical formula to which an amount of substance refers. –1 mole of oxygen could either refer to oxygen atoms, O, or to oxygen molecules, O 2 –1 mole of O or 1 mole of O 2 is clearer

6. Working in multiples of 1 mol For carbon: –1.00 mol of C atoms has a mass of 12.0g –2.00 mol of C atoms has a mass of 24.0g –0.50 mol of C atoms has a mass of 6.0g

7. How big is a mole One mole of coarse sand would cover the surface of the UK to a depth of 1500km

8. Simple Calculations with Moles THi Notes

9. Problems Relative atomic masses: H = 1; O = 16; Na = 23; Cl = 35.5; Ca = 40; Cu = 64 1.What is the mass of 4 mol of sodium chloride, NaCl? 2.How many moles is 37g of calcium hydroxide, Ca(OH) 2 ? 3.How many moles is 1kg of calcium? 4.What is the mass of 0.125 mol of copper oxide, CuO? 5.0.1 mol of a substance weighs 4g. What is the weight of 1 mole? 6.0.004 mol of a substance weighs 1g. What is the relative formula mass of the compound?