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Standard XII

Chemistry

Real Gases

In an experim...

Question

In an experiment, $10$ L of air (containing $O_{3}$ ) at $1$ atm and $27^{o} C$ was passed through an alkaline KI solution. After neutralisation, free iodine requires $1.5$ mL of $0.01 N N a_{2} S_{2} O_{3}$ solution. The molar percentage of $O_{3}$ in air is $y \times 10^{- 4}$ . Here $y$ is (in nearest integer) :

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Solution

Moles of ozone $=$ Moles of iodine $= 2$ moles of $N a_{2} S_{2} O_{3}$
Moles of $N a_{2} S_{2} O_{3} = 1.5 \times 10^{- 3} \times 0.01 = 1.5 \times 10^{- 5}$
This is equal to the number of moles of ozone.
$22.4$ L of a gas at STP corresponds to $1$ mole.

Hence, the number of moles in $10$ L of air $= \frac{10}{22.4} = 0.4464$ moles

Mole percentage of ozone $= \frac{2 \times 1.5 \times 10^{- 5}}{0.4464} \times 100 = 0.00336$ $= 6.16 \times 10^{- 4}$

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In an experiment, 10 L of air (containing O3) at 1 atm and 27oC was passed through an alkaline KI solution. After neutralisation, free iodine requires 1.5 mL of 0.01NNa2S2O3 solution. The molar percentage of O3 in air is y×10−4. Here y is (in nearest integer) :