- gives numbers of moles reacting C2 3.4 Equations and calculations H2 + O2 H2O 2 2 2 moles H2 2 x (1x2) = 4 g 1 mole O2 (16 x2) = 32 g 2 mole H2O 2x (1+1 + 16) = 36 g Q. How many grams of Hydrogen and oxygen are needed to make 72g water ? H =1 O = 16 1. Balance the equation - gives numbers of moles reacting 2. Calculate masses reacting - from the RAMs 3. Divide by molar quantity and x by 72g

3. Divide by molar quantity and x by 72g C2 3.4 Equations and calculations H2 + O2 H2O 2 2 2 moles H2 2 x (1x2) = 4 g 1 mole O2 (16 x2) = 32 g 2 mole H2O 2x (1+1 + 16) = 36 g 4 x 72g = 8 g 36 Hydrogen 32 x 72g = 64 g 36 Oxygen 36 x 72g = 72g 36 Water 3. Divide by molar quantity and x by 72g

C2 3.4 Equations Ca CO3 CaO + CO2 heat and calculations limestone lime 1 mole CaCO3 40+ 12+ (16x3) = 100 g 1 mole CaO 40 + 16 = 56 g 1 mole CO2 12 + (16x2) = 44 g Q. How many tonnes of lime could be obtained from 250 tonnes of limestone? H =1 O = 16 Ca 40 C= 12 1 tonne = 1,000,000g 1. Balance the equation - gives numbers of moles reacting 2. Calculate masses reacting - from the RAMs 3. Divide by molar quantity and x by 250 tonnes

C2 3.4 Equations and calculations Ca CO3 CaO + CO2 limestone lime heat 1 mole CO2 12 + (16x2) = 44 g 1 mole CaO 40 + 16 = 56 g 1 mole CaCO3 40+ 12+ (16x3) = 100 g 44 x 250 = 110 100 tonnes of CO2 100 x 250 = 250 100 tonnes of Limestone 56 x 250 = 140 100 tonnes of lime Q. How many tonnes of lime could be obtained from 250 tonnes of limestone? H =1 O = 16 Ca 40 C= 12 1 tonne = 1,000,000g 3. Divide by molar quantity and x by 250 tonnes

e b mo ma p H2O2 H2O + O2 2 2 Calculate masses reacting - from the RAMs Then divide each term by 80 then multiply each term by 60 2x 40g + 1(16x2)g gives 2 (40 +16)g So 60g calcium reacts with 24 g oxygen