$10 \mathrm{~g}$ of hydrogen and 64 of oxygen were filled in a steel vessel and exploded. Amount of water…

$10 \mathrm{~g}$ of hydrogen and 64 of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be
  1. $2 \mathrm{~mol}$
  2. $3 \mathrm{~mol}$
  3. $4 \mathrm{~mol}$
  4. $1 \mathrm{~mol}$

Solution

Key Idea (i) $\mathrm{H}_2+\frac{1}{2} \mathrm{O}_2 \longrightarrow \mathrm{H}_2 \mathrm{O}$ (ii) Amount of water produced is decided by limited reactant (ie, the reactant which is used in small amount) $\begin{aligned} & \mathrm{H}_2+\frac{1}{2} \mathrm{O}_2 \longrightarrow \mathrm{H}_2 \mathrm{O} \\ & 1 \mathrm{~mol} \quad \frac{1}{2} \mathrm{~mol} \quad 1 \mathrm{~mol} \\ & \frac{10}{2} \mathrm{~mol} \quad \frac{64}{32} \mathrm{~mol} \\ & =5 \mathrm{~mol}=2 \mathrm{~mol} \\ & \because \frac{1}{2} \mathrm{molO}_2 \text { gives }=1 \mathrm{~mol} \mathrm{H}_2 \mathrm{O} \\ & \therefore 2 \mathrm{~mol} \mathrm{O}_2 \text { will give }=1 \times 2 \times 2=4 \mathrm{~mol} . \end{aligned}$

Asked in: NEET 2009 (Screening)

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