A mixture of nitrogen and hydrogen gases, at a total pressure of 663 mm Hg, contains 3.46 grams of nitrogen and 0.156 grams of hydrogen. What is the partial pressure of each gas in the mixture? PN2 = mm Hg PH2 = mm Hg

Respuesta :

Answer: The partial pressure of nitrogen gas is 405.76 mmHg and that of hydrogen gas is 257.24 mmHg

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

  • For nitrogen gas:

Given mass of nitrogen gas = 3.46 g

Molar mass of nitrogen gas = 28 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of nitrogen gas}=\frac{3.46g}{28g/mol}=0.123mol[/tex]

  • For hydrogen gas:

Given mass of hydrogen gas = 0.156 g

Molar mass of hydrogen gas = 2 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of hydrogen gas}=\frac{0.156g}{2g/mol}=0.078mol[/tex]

Mole fraction of a gas is calculated by using the formula:

[tex]\chi_{A}=\frac{n_{A}}{n_{A}+n_{B}}[/tex]      ......(1)

  • For nitrogen gas:

Putting values in equation 1, we get:

[tex]\chi_{\text{nitrogen gas}}=\frac{0.123}{0.123+0.078}=0.612[/tex]

  • For hydrogen gas:

Putting values in equation 1, we get:

[tex]\chi_{\text{hydrogen gas}}=\frac{0.078}{0.123+0.078}=0.388[/tex]

The partial pressure of a gas is given by Raoult's law, which is:

[tex]p_A=p_T\times \chi_A[/tex]     ......(2)

where,

[tex]p_A[/tex] = partial pressure of substance A

[tex]p_T[/tex] = total pressure  = 663 mmHg

[tex]\chi_A[/tex] = mole fraction of substance A

  • For nitrogen gas:

[tex]p_{\text{Nitrogen gas}}=663mmHg\times 0.612\\\\p_{\text{Nitrogen gas}}=405.76mmHg[/tex]

  • For hydrogen gas:

[tex]p_{\text{Hydrogen gas}}=663mmHg\times 0.388\\\\p_{\text{Hydrogen gas}}=257.24mmHg[/tex]

Hence, the partial pressure of nitrogen gas is 405.76 mmHg and that of hydrogen gas is 257.24 mmHg