The complete combustion of copper(I) sulphide is according to the following equation: 2Cu2S(s) + 302(g) →→2Cu2O(s) + 2SO2(g)
If the mass of Cu2S in the mixture is 14.0 g, calculate
(a) the number of molecules of oxygen gas reacted.
(b) the mass of SO2 gas produced.
(c)the volume of SO2 gas at STP

a) 7.94 x 10²³ molecules, b) 5.62 g SO2, c) 1.97 L

Explanation:

a) We need to first convert Cu2S to moles. Since molar mass of Cu2S is 159.14 g/mol, 14.0 g = 0.0880 mol. Using molar ratios (3 mol O2/2 mol Cu2S, 0.0880 mol of Cu2S = 0.132 mol O2. Since 1 mol contains 6.02 x 10²³ molecules, 0.132 mol O2 = 7.94 x 10²² molecules O2.

b) Since the molar ratios of Cu2S to SO2 is 1:1, 0.0880 mol of Cu2S produces 0.0880 mol SO2. To convert mol to grams, we use the molar mass of SO2 (64.06 g/mol) to figure out that 0.0880 mol SO2 = 5.63 g SO2.

c) At STP, 1 mol occupies 22.4 liters. 0.0880 mol SO2 x 22.4 L/1 mol = 1.97 L

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