Chloroform is a volatile liquid once commonly used in the laboratory but now being phased out due to its ozone depletion potential.If the pressure of gaseous chloroform in a flask is 195 mm Hg at 25°C and its density is 1.25 g/L,what is the molar mass of chloroform?
A)10.0 g/mol
B)76.3 g/mol
C)119 g/mol
D)None of these

Question

Quizplus · Accepted Answer

Using the ideal gas law equation in the form of $PV = nRT$, where $n = \frac{m}{M}$ (m is mass, M is molar mass), and given density ($\rho = \frac{m}{V}$), we can rearrange to find $M = \frac{RT}{P} \times \rho$. Substituting $R = 0.0821 \, \text{L atm K}^{-1} \text{mol}^{-1}$, $T = 298 \, \text{K}$ (25°C + 273), $P = 195 \, \text{mm Hg} \times \frac{1 \, \text{atm}}{760 \, \text{mm Hg}}$, and $\rho = 1.25 \, \text{g/L}$, we calculate $M$ to be approximately $119 \, \text{g/mol}$.

Chloroform Is a Volatile Liquid Once Commonly Used in the Laboratory