of an impure sample of reacts with to give of at STP. The percentage purity is: β Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
$5 \text{ g}$ of an impure sample of $Zn$ reacts with $HCl$ to give $1.12 \text{ L}$ of $H_2$ at STP. The percentage purity is:
Answer: A
π‘ Solution & Explanation
$\text{Moles } H_2 = 1.12/22.4 = 0.05$. $\text{Moles } Zn = 0.05$. $\text{Mass pure Zn} = 0.05 \times 65.4 \approx 3.27 \text{ g}$. $\% = (3.27/5) \times 100 \approx 65\%$.
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