The question is incomplete, here is the complete question:
At 20°C the vapor pressure of benzene [tex](C_6H_6)[/tex] is 75 torr, and that of toluene [tex](C_7H_8)[/tex] is 22 torr. Assume that benzene and toluene form an ideal solution.
What is the mole fraction of benzene in the solution that has a vapor pressure of 38 torr at 20°C? Express your answer using two significant figures.
Answer: The mole fraction of benzene is 0.302
Explanation:
Let the mole fraction of benzene be 'x' and that of toluene is '1-x'
To calculate the total pressure of the mixture of the gases, we use the equation given by Raoult's law, which is:
[tex]p_T=\sum_{i=1}^n(\chi_{i}\times p_i)[/tex]
We are given:
Vapor pressure of benzene = 75 torr
Vapor pressure of toluene = 22 torr
Vapor pressure of solution = 38 torr
Putting values in above equation, we get:
[tex]38=[(75\times x)+(22\times (1-x))]\\\\x=0.30[/tex]
Hence, the mole fraction of benzene is 0.30
