Question

p_A and p_B are the vapour pressure of pure liquid components, A and B, respectively of an ideal binary solution. If χ_A represents the mole fraction of component A, the total pressure of the solution will be ______.

Options

• p_A + χ_A(p_B − p_A)

• p_A + χ_A(p_A − p_B)

• p_B + χ_A(p_B − p_A)

• p_B + χ_A(p_A − p_B)

Answer 1

p_A and p_B are the vapour pressure of pure liquid components, A and B, respectively of an ideal binary solution. If χ_A represents the mole fraction of component A, the total pressure of the solution will be p_B + χ_A(p_A − p_B).

Explanation:

For an ideal binary solution, total vapour pressure is

`P_"total" = p_A^circ chi_A + p_B^circ chi_B`

Since χ_B = 1 − χ_A, we can rewrite

`P_"total" = p_A chi_A + p_B (1 - chi_A)`

= p_B + χ_A(p_A − p_B)