4.What volume of hydrogen gas at STP is produced when 2.5 grams of zinc react with an
excess of hydrochloric acid?
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Answer:
0.86
Explanation:
1mol of Zn has mass of 65.39g.The amount of Zn is 2.5g65.39g/mol=0.038mol.
The amount of H2 produced is the same as the amount of Zn consumed (0.038mol).
1mol of ideal gas will occupy 22.4L at STP.
The H2 will occupy 0.038mol×22.4L/mol=0.86L
.