Stoichiometry
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1. The document discusses stoichiometry and provides 4 examples of stoichiometry calculations. 2. The first example calculates the mass of magnesium oxide formed from the reaction of 0.6g of magnesium. It determines 0.025 moles of magnesium react to form 0.025 moles of magnesium oxide, yielding 1.0g of magnesium oxide. 3. The second example calculates the volume of carbon dioxide released from the reaction of 5g of calcium carbonate. It determines 0.05 moles of calcium carbonate react to release 0.05 moles of carbon dioxide, yielding a volume of 1.2dm^3.
Stoichiometry
- 2. Example 1: 2Mg + O2 2MgO 0.025 mol 0.025 mol What is the mass of the oxide formed if 0.6 g of magnesium is burnt in excess oxygen? Number of moles of Mg = = 0.025 mol 0.6 24 2
- 3. Stoichiometry: From the equation : 2 moles of magnesium, Mg produce 2 moles of magnesium oxide, MgO From the calculation : 0.025 mole of magnesium, Mg produce 0.025 mole of magnesium oxide, MgO Therefore, mass of MgO Mass = 0.025 x 40 = 1.0 g n =_mass___ molar mass 3
- 4. Example 2: CaCO3+ 2HCl CaCl2 + H2O+ CO2 0.05 mol 0.05 mol What is the volume of carbon dioxide released when 5 g of calciumcarbonate reacts with hydrochloric acid at roomcondition? Number of moles of CaCO3 = = 5.0 100 0.05 mol 4
- 5. Stoichiometry: From the equation : 1 mole of calcium carbonate, CaCO3 produce 1 mole of carbon dioxide, CO2 From the calculation : 0.05 mole of calcium carbonate, CaCO3 produce 0.05 mole of carbon dioxide, CO2 Therefore, volume of CO2: Volume = 0.05 x 24 = 1.2 dm¯³ n =_volume__ molar volume 5
- 6. Example 3: 5.0 g of hydrated copper(II) sulphate, CuSO4.5H2O is heated to remove its water vapour. Calculate the mass of watervapour removed. CuSO4.5H2O CuSO4 + 5H2O Number of moles of CuSO4.5H2O = = 6
- 7. Stoichiometry: From the equation : .............................................................................................. .............................................................................................. ........................................................................................... From the calculation : …………………………………………………………………… …………………………………………………………………… …………………………………………………………………… Therefore, mass of water vapour : Mass = = 7
- 8. Example 4 3.1 g of sodiumoxide is formed when the sodium metal is burnt completely in oxygen at STP. Calculate the volume used. 4Na + O2 2Na2O Number of moles of Na2O = = 8
- 9. Stoichiometry: From the equation : ………………………………………………………… ………………………………………………………… ………………………………………………………… From the calculation : .……….. ………………………………………………………… ………………………………………………………… ……………………………………………… Therefore, volume of oxygen: 9
- 10. Stoichiometry: From the equation : ………………………………………………………… ………………………………………………………… ………………………………………………………… From the calculation : .……….. ………………………………………………………… ………………………………………………………… ……………………………………………… Therefore, volume of oxygen: 9