All Exams Test series for 1 year @ ₹349 only
Question

At 298 K, the mole percentage of $\text{N}_2\text{(g)}$ in air is 80%. Water is in equilibrium with air at a pressure of 10 atm. What is the mole fraction of $\text{N}_2\text{(g)}$ in water at 298 K?
($K_H \text{ for } \text{N}_2 \text{ is } 6.5 \times 10^7 \text{ mm Hg}$)

The correct answer is
$9.35 \times 10^{-5}$

Solving for Nitrogen Mole Fraction in Water

This solution calculates the mole fraction of nitrogen ($\text{N}_2$) dissolved in water using Henry's Law, based on the air composition, total pressure, and the provided Henry's Law constant ($K_H$).

Key Information Provided

  • Temperature: 298 K
  • Total Pressure ($P_{total}$): 10 atm
  • Mole percentage of $\text{N}_2$ in air: 80%
  • Henry's Law Constant ($K_H$) for $\text{N}_2$: $6.5 \times 10^7$ mm Hg

Step 1: Determine Mole Fraction of N₂ in Air

The mole percentage of $\text{N}_2$ in air is given as 80%. Convert this percentage to a mole fraction ($x_{\text{N}_2, \text{air}}$):

$x_{\text{N}_2, \text{air}} = \frac{80}{100} = 0.80$

Step 2: Calculate Partial Pressure of N₂

Convert the total pressure from atm to mm Hg to match the units of the Henry's Law constant.

$P_{total} = 10 \text{ atm} \times 760 \frac{\text{mm Hg}}{\text{atm}} = 7600 \text{ mm Hg}$

Calculate the partial pressure of $\text{N}_2$ ($P_{\text{N}_2}$) above the water using its mole fraction in air and the total pressure:

$P_{\text{N}_2} = x_{\text{N}_2, \text{air}} \times P_{total}$

$P_{\text{N}_2} = 0.80 \times 7600 \text{ mm Hg} = 6080 \text{ mm Hg}$

Step 3: Apply Henry's Law to Find Mole Fraction in Water

Henry's Law is expressed as $P_{gas} = K_H \times x_{gas}$, where $x_{gas}$ is the mole fraction of the gas in the liquid. Rearrange the formula to solve for the mole fraction of $\text{N}_2$ in water ($x_{\text{N}_2, \text{water}}$):

$x_{\text{N}_2, \text{water}} = \frac{P_{\text{N}_2}}{K_H}$

Substitute the calculated partial pressure and the given Henry's Law constant:

$x_{\text{N}_2, \text{water}} = \frac{6080 \text{ mm Hg}}{6.5 \times 10^7 \text{ mm Hg}}$

$x_{\text{N}_2, \text{water}} \approx 0.93538 \times 10^{-4}$

$x_{\text{N}_2, \text{water}} \approx 9.35 \times 10^{-5}$

Final Answer

The mole fraction of $\text{N}_2\text{(g)}$ in water at 298 K is determined to be approximately $9.35 \times 10^{-5}$.

Was this answer helpful?

Similar Questions

  1. X and Y are the number of electrons involved, respectively during the oxidation of $\text{I}^-$ to $\text{I}_2$ and $\text{S}^{2-}$ to S by acidified $\text{K}_2\text{Cr}_2\text{O}_7$. The value of X + Y is ______.
  2. Consider two Group IV metal ions $\text{X}^{2+}$ and $\text{Y}^{2+}$.
    A solution containing 0.01 M $\text{X}^{2+}$ and 0.01 M $\text{Y}^{2+}$ is saturated with $\text{H}_2\text{S}$. The pH at which the metal sulphide YS will form as a precipitate is ______. (Nearest integer)
    (Given: $\text{K}_{sp}(\text{XS}) = 1 \times 10^{-22}$ at $25^\circ\text{C}$, $\text{K}_{sp}(\text{YS}) = 4 \times 10^{-16}$ at $25^\circ\text{C}$, $[\text{H}_2\text{S}] = 0.1\text{M}$ in solution, $\text{K}_{a1} \times \text{K}_{a2}(\text{H}_2\text{S}) = 1.0 \times 10^{-21}$, $\log 2 = 0.30$, $\log 3 = 0.48$, $\log 5 = 0.70$)
  3. Electricity is passed through an acidic solution of $\text{Cu}^{2+}$ till all the $\text{Cu}^{2+}$ was exhausted, leading to the deposition of 300 mg of Cu metal. However, a current of 600 mA was continued to pass through the same solution for another 28 minutes by keeping the total volume of the solution fixed at 200 mL. The total volume of oxygen evolved at STP during the entire process is ______ mL. (Nearest integer)
    [Given:
    $\text{Cu}^{2+}\text{(aq)} + 2\text{e}^- \rightarrow \text{Cu(s)} \quad \text{E}^\circ_{\text{red}} = +0.34 \text{ V}$
    $\text{O}_2\text{(g)} + 4\text{H}^+ + 4\text{e}^- \rightarrow 2\text{H}_2\text{O} \quad \text{E}^\circ_{\text{red}} = +1.23 \text{ V}$
    Molar mass of Cu = $63.54 \text{ g mol}^{-1}$
    Molar mass of $\text{O}_2$ = $32 \text{ g mol}^{-1}$
    Faraday Constant = $96500 \text{ C mol}^{-1}$
    Molar volume at STP = 22.4 L]
  4. Two liquids A and B form an ideal solution at temperature T K. At T K, the vapour pressures of pure A and B are 55 and $15 \text{ kN m}^{-2}$ respectively. What is the mole fraction of A in solution of A and B in equilibrium with a vapour in which the mole fraction of A is 0.8?
  5. The heat of atomisation of methane and ethane are 'x' $\text{kJ mol}^{-1}$ and 'y' $\text{kJ mol}^{-1}$ respectively. The longest wavelength ($\lambda$) of light capable of breaking the C–C bond can be expressed in SI unit as:
  6. A student has planned to prepare acetanilide from aniline using acetic anhydride.
    The student has started from $9.3 \text{ g}$ of aniline. However, the student has managed to obtain $11 \text{ g}$ of dry acetanilide.
    The % yield of this reaction is :-
  7. The half-life of ${}^{65}\text{Zn}$ is 245 days. After x days, 75% of original activity remained. The value of $x$ in days is _______. (Nearest integer)
    (Given: $\log 3 = 0.4771$ and $\log 2 = 0.3010$)
  8. Molar conductivity of a weak acid HQ of concentration $0.18 \text{ M}$ was found to be $1/30$ of the molar conductivity of another weak acid HZ with concentration of $0.02 \text{ M}$. If $\lambda^\circ_{Q^-}$ happened to be equal with $\lambda^\circ_{Z^-}$, then the difference of the $\text{pK}_a$ values of the two weak acids ($\text{pK}_a\text{(HQ)} - \text{pK}_a\text{(HZ)}$) is _______ (Nearest integer).
    [Given: degree of dissociation ($\alpha$) < < 1 for both weak acids, $\lambda^\circ$ : limiting molar conductivity of ions]
  9. Consider the following data :
    $\Delta_f \text{H}^\ominus (\text{methane, g}) = -X \text{ kJ mol}^{-1}$
    Enthalpy of sublimation of graphite $= Y \text{ kJ mol}^{-1}$
    Dissociation enthalpy of $\text{H}_2 = Z \text{ kJ mol}^{-1}$
    The bond enthalpy of $\text{C}-\text{H}$ bond is given by :
  10. The first and second ionization constants of $\text{H}_2\text{X}$ are $2.5 \times 10^{-8}$ and $1.0 \times 10^{-13}$ respectively. The concentration of $\text{X}^{2-}$ in $0.1\text{ M}$ $\text{H}_2\text{X}$ solution is __________ $\times 10^{-15}\text{ M}$. (Nearest Integer)

Important Questions from Physical Chemistry

  1. X and Y are the number of electrons involved, respectively during the oxidation of $\text{I}^-$ to $\text{I}_2$ and $\text{S}^{2-}$ to S by acidified $\text{K}_2\text{Cr}_2\text{O}_7$. The value of X + Y is ______.
  2. Consider two Group IV metal ions $\text{X}^{2+}$ and $\text{Y}^{2+}$.
    A solution containing 0.01 M $\text{X}^{2+}$ and 0.01 M $\text{Y}^{2+}$ is saturated with $\text{H}_2\text{S}$. The pH at which the metal sulphide YS will form as a precipitate is ______. (Nearest integer)
    (Given: $\text{K}_{sp}(\text{XS}) = 1 \times 10^{-22}$ at $25^\circ\text{C}$, $\text{K}_{sp}(\text{YS}) = 4 \times 10^{-16}$ at $25^\circ\text{C}$, $[\text{H}_2\text{S}] = 0.1\text{M}$ in solution, $\text{K}_{a1} \times \text{K}_{a2}(\text{H}_2\text{S}) = 1.0 \times 10^{-21}$, $\log 2 = 0.30$, $\log 3 = 0.48$, $\log 5 = 0.70$)
  3. Electricity is passed through an acidic solution of $\text{Cu}^{2+}$ till all the $\text{Cu}^{2+}$ was exhausted, leading to the deposition of 300 mg of Cu metal. However, a current of 600 mA was continued to pass through the same solution for another 28 minutes by keeping the total volume of the solution fixed at 200 mL. The total volume of oxygen evolved at STP during the entire process is ______ mL. (Nearest integer)
    [Given:
    $\text{Cu}^{2+}\text{(aq)} + 2\text{e}^- \rightarrow \text{Cu(s)} \quad \text{E}^\circ_{\text{red}} = +0.34 \text{ V}$
    $\text{O}_2\text{(g)} + 4\text{H}^+ + 4\text{e}^- \rightarrow 2\text{H}_2\text{O} \quad \text{E}^\circ_{\text{red}} = +1.23 \text{ V}$
    Molar mass of Cu = $63.54 \text{ g mol}^{-1}$
    Molar mass of $\text{O}_2$ = $32 \text{ g mol}^{-1}$
    Faraday Constant = $96500 \text{ C mol}^{-1}$
    Molar volume at STP = 22.4 L]
  4. Two liquids A and B form an ideal solution at temperature T K. At T K, the vapour pressures of pure A and B are 55 and $15 \text{ kN m}^{-2}$ respectively. What is the mole fraction of A in solution of A and B in equilibrium with a vapour in which the mole fraction of A is 0.8?
  5. The heat of atomisation of methane and ethane are 'x' $\text{kJ mol}^{-1}$ and 'y' $\text{kJ mol}^{-1}$ respectively. The longest wavelength ($\lambda$) of light capable of breaking the C–C bond can be expressed in SI unit as:
Need Expert Advice?
More Questions from JEE Main

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App