Answer:
<em>molar mass of the phosphorus chloride = 138.06 g/mol</em>
<em></em>
Explanation:
<em>mass of phosphorus will be the same as mass of CO2, since it is stated that they are of equal amount.</em>
mass = 3.51 g
<em>lets assume that it took the CO2 1 sec to effuse, then the time taken by the phosphorus chloride will be 1.77 sec</em>
From this we can say that
rate of effusion of CO2 = 3.51/1 = 3.51 g/s
rate of effusion of the phosphorus chloride = 3.51/1.77 = 1.98 g/s
<em>From graham's equation of effusion</em>,
= 
Rc = rate of effusion of CO2 = 3.51 g/s
Rp = rate of effusion of phosphorus chloride = 1.98 g/s
Mc = molar mass of CO2 = 44.01 g/mol
Mp = molar mass of the phosphorus chloride = ?
Imputing values into the equation, we have
= 
1.77 = 
11.75 = 
Mp = 
Mp = <em>molar mass of the phosphorus chloride = 138.06 g/mol</em>