Question

Calculate the concentration of nitrogen present in the water. Assuming that the temperature is ${25}^{o}C$, total pressure is $1atm$ and mole fraction of nitrogen is $0.78$ [$K_H$ for nitrogen $=8.42\times {10}^{-7}M/mmHg$]

• A. $4.99M$
• B. $4.99\times {10}^{-2}M$
• C. $4.99\times {10}^{-4}M$
• D. $Noneoftheabove$

Answer 1

The correct option is D $Noneoftheabove$

$P_{N_2}=1atmosphere$
$P_{N_2}=K_H\times N_2$
By Henrys law
$x{N}_2=\frac{P_{N_2}}{K_H}=\frac{1}{8.42\times 10^{-7}}$
$x{N}_2=\frac{n\left(N_2\right)}{n\left(N_2\right)+n\left(H_{2}O\right)}$
$x{N}_2=\frac{n\left(N_2\right)}{n\left(H_{2}O\right)}$

$n\left(N_2\right)=x{N}_2.n\left(H_{2}O\right)$
$n\left(N_2\right)=x{N}_2.\frac{1000}{18}$
$\Rightarrow \frac{1}{8.42\times 10^{-7}}\times 55.5$
$\Rightarrow 6.59\times 10^{7}moles$
conclusion: here the answer option(d) is correct.