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Multiple Choice
If you have 3.2 grams of Zn, how many liters of H2 gas could be produced in the following chemical reaction at STP? Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)
A
0.56 liters
B
3.36 liters
C
1.12 liters
D
2.24 liters
Verified step by step guidance
1
Identify the balanced chemical equation: Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g). This tells us that 1 mole of Zn produces 1 mole of H2 gas.
Calculate the molar mass of Zn. The atomic mass of Zn is approximately 65.38 g/mol.
Determine the number of moles of Zn you have by dividing the mass of Zn by its molar mass: \( \text{moles of Zn} = \frac{3.2 \text{ g}}{65.38 \text{ g/mol}} \).
Use the stoichiometry of the reaction to find the moles of H2 gas produced. Since the ratio of Zn to H2 is 1:1, the moles of H2 will be the same as the moles of Zn.
At STP (Standard Temperature and Pressure), 1 mole of any gas occupies 22.4 liters. Multiply the moles of H2 by 22.4 L/mol to find the volume of H2 gas produced.