Question

What volume of hydrogen gas is given off when excess zinc is added to 50cm3 of 2.0 mol/dm3 hydrochloric acid? (Note: the volume of gas measured at STP).
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Answer 1

Answer:

Balanced reaction is:

Zn+2HCl→ZnCl

2

+H

2

Molar mass of Zn= 65.4 g/mol

thus 65.4 g of zinc liberates 1 mol i.e. 22.4 L hydrogen gas at STP

32.65 g of zinc will liberate:

65.4

22.4

×32.65=11.18L of hydrogen gas at STP