Question

question 4 of 29
calculate the vapor pressure of benzene, c₆h₆, at 25 °c in an ideal solution containing 1.65 mol of benzene and 0.492 mol of toluene. the vapor pressure of pure benzene is 96.0 torr.
p_benzene=
calculate the vapor pressure of toluene, c₇h₈, at 25 °c in an ideal solution containing 1.65 mol of benzene and 0.492 mol of toluene. the vapor pressure of pure toluene is 27.0 torr.
p_toluene=

Explanation:

Step1: Calculate mole fraction of benzene

The mole - fraction of benzene ($X_{benzene}$) is calculated using the formula $X_{benzene}=\frac{n_{benzene}}{n_{benzene} + n_{toluene}}$, where $n_{benzene}=1.65$ mol and $n_{toluene}=0.492$ mol.
$X_{benzene}=\frac{1.65}{1.65 + 0.492}=\frac{1.65}{2.142}\approx0.770$

Step2: Calculate vapor pressure of benzene

According to Raoult's law, $P_{benzene}=X_{benzene}\times P_{benzene}^0$, where $P_{benzene}^0 = 96.0$ torr.
$P_{benzene}=0.770\times96.0 = 73.92$ torr

Step3: Calculate mole fraction of toluene

The mole - fraction of toluene ($X_{toluene}$) is calculated using the formula $X_{toluene}=\frac{n_{toluene}}{n_{benzene}+n_{toluene}}$.
$X_{toluene}=\frac{0.492}{1.65 + 0.492}=\frac{0.492}{2.142}\approx0.230$

Step4: Calculate vapor pressure of toluene

According to Raoult's law, $P_{toluene}=X_{toluene}\times P_{toluene}^0$, where $P_{toluene}^0 = 27.0$ torr.
$P_{toluene}=0.230\times27.0 = 6.21$ torr

Answer:

$P_{benzene}=73.92$ torr
$P_{toluene}=6.21$ torr