Chapter 3

• A unit; the amount of a substance that contains 6.02x10^23 of those particles

• The number of particles in each mole of carbon-12; 6.02x10^23 • Its symbol is N subscript A • Its unit is mol^-1

• The relative atomic mass of its atom (/atoms added together) in grams

• The mass per mole of a substance • Its symbol is M • Its unit is g mol^-1

• Amount of substance, n (moles, mol)= mass, m (grams, g)/ molar mass, M (g mol^-1)

• The number of atoms of each element in a molecule

• The simplest whole-number ratio of atoms of each element in a compound

• Water molecules that are bonded into the crystalline structure of a compound

• Bonds holding the water within the crystal are broken, and the water is driven off • Anhydrous copper (II) sulfate is left behind • CuSO4∙5H2O -> CUSO4 + 5H2O

• Weigh an empty crucible • Add the salt to the crucible, and weigh them together • Using a pipe clay triangle, tripod, Bunsen burner and heatproof mat, heat the crucible • Leave the crucible to cool, and weigh it with the anhydrous salt inside • Heat it again, leave it to cool and weigh it • Repeat the process until the final mass reading no longer changes

• All of the water has been driven off • There has been no further decomposition of the reactant

• You “heat to a constant mass” • If you don’t do this, your calculated value for the water of crystallisation will be too small, as your calculated mass of water would have been too small

• Your calculated value for the water of crystallisation will be too big, as you’ve lost more mass than just the water’s mass • There may be a colour change, but sometimes there isn’t, so it can be hard to tell

• The volume per mole of gas • dm^3 mol^-1

• 24 dm^3 mol^-1 (1 mole of gas molecules take up 24dm^3 at RTP)

• When gases are at different temperatures and pressures to RTP • For more accurate calculations

• pV= nRT • p= pressure (Pascals, Pa) • V= volume (m^3) • n= amount of substance (moles, mol) • R= ideal gas constant: 8.314 (J mol^-1 K^-1) • T= temperature (Kelvin, K)

• The reaction may not have gone to completion • Other (side) reactions may have also taken place • Purifying the product may cause some of it to be lost

• Gases need to be cooled to room temperature before measuring their volume if using the formula for gases at RTP

• (Actual yield/ theoretical yield) x100

• A measure of how well atoms have been utilised • (sum of molar masses of desired products/ sum of molar masses of all products) x100

• Preserves raw materials • Reduces waste

• [(Uncertainty × multiplied by how many readings you take) ÷ (amount recorded)] × 100

• This would lead to a larger titre • Having a larger titre leads to a smaller percentage uncertainty