Task 1.2c

1. What amounts of substance are the following masses?
(a) 8g of S, (b) 8g of O, (c) 8g of O₂, (d) 0.5g of H₂, (e)25g of NaOH
2. What are the masses of the following amounts?
(a) 2mol of Cl₂, (b) 0.5 mol of CuO, (c) 0.1 mol of H₂SO₄, (d) 2.5mol of NaHCO₃.
3. What mass of glucose can be fermented to give 5.00g of ethanol?
C₆H₁₂O₆(aq) -----> 2C₂H₅OH(aq) + 2CO₂(g)
4. What mass of silver chloride can be precipitated from a solution which contains 1.00*10-3 mol of silver ions?
Ag⁺(aq) + Cl^-(aq) -----> AgCl(s)
5. The pollutant, sulphur dioxide, can be removed from the air by the reaction
2CaCO₃(s) + 2SO₂(g) +O₂(g) -----> 2CaSO₄(s) + 2CO₂(g)
What mass of calcium carbonate is needed to remove 10.0g of SO₂?
6. What mass of sodium carbonate can be made by heating 100g of sodium hydrogencarbonate?
2NaHCO₃(s)  -----> Na₂CO₃(s) + CO₂(g) H₂O(g)

Answers:

1. (a) 8g/32gmol^-1 = 0.25mol, (b) 0.5mol (c)0.25mol (d) 0.25mol (e) 0.625mol
2. (a) 2mol*71gmol^-1 = 142g, (b) 40g, (c)9.8g, (d) 210g.
3. 8.91g
4. 0.144g
5. 15.6g
6. 63.1g