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

Answer : The correct option is, (C) 119 g/mol

Explanation :

To calculate the molar mass of chloroform we are using ideal gas equation:

where,

P = pressure of gas = 195 mmHg = 0.256 atm    (1 atm = 760 mmHg)

V = volume of argon gas

T = temperature of gas =

R = gas constant = 0.0821 L.atm/mole.K

w = mass of gas

= density of gas = 1.25 g/L

M = molar mass of chloroform = ?

Now put all the given values in the ideal gas equation, we get:

Therefore, the molar mass of chloroform is, 119 g/mol.