Question

On passing silent electric discharge through oxygen in an ozonizer, $5.5\, mol \%$ of oxygen is converted to ozone. How many moles of $O_2$ and $O_3$ result when $35$ moles of $O_2$ is originally present?

• A. 33
• B. 34.4
• C. 35
• D. 31.8

Answer 1

Answer: (B)

34.4

Answer 2

$3 O _{2} \longrightarrow 2 O _{3}$ or $O _{2} \longrightarrow \frac{2}{3} O _{3}$ According to question, $5.5\,mol \%$ of $O _{2}$ is converted into $O _{3}$ $\therefore 35-\frac{35 \times 5.5}{100}$ moles of$O _{2}$ $=\frac{35 \times 5.5}{100} \times \frac{2}{3}$ moles $O _{3}$ $33.075$ moles of $O _{2}=1.28$ moles of $O _{3}$ Thus, total number of moles present originally was $=33.075$ of $O _{2}+1.28$ of $O _{3}$ $=34.4$ moles