Question

On a clear day at sea level, with a temperature of 25 °C, the partial pressure of N2 in air is 0.78 atm and the concentration of nitrogen in water is 5.3⋅10−4 M. When the partial pressure of N2 is ________ atm, the concentration in water is 2.0⋅10−3 M.

Answer 1

Answer : The partial pressure of nitrogen gas is, 2.94 atm

Explanation:

According top the Henry's Law, the concentration of a gas in a liquid is directly proportional to the partial pressure of the gas.

$C\propto P$

$C=K_H\times P$

$K_H$ is Henry's constant.

or,

$\frac{C_1}{C_2}=\frac{P_1}{P_2}$

where,

$C_1$ = initial concentration of gas = $5.3\times 10^{-4}M$

$C_2$ = final concentration of gas = $2.0\times 10^{-3}M$

$P_1$ = initial partial pressure of gas = 0.78 atm

$P_2$ = final partial pressure of gas = ?

Now put all the given values in the above formula, we get the final partial pressure of the gas.

$\frac{5.3\times 10^{-4}M}{2.0\times 10^{-3}M}=\frac{0.78atm}{P_2}$

$P_2=2.94atm$

Therefore, the partial pressure of nitrogen gas is, 2.94 atm