A 0.429-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?
A)8.9 g/mol
B)66 g/mol
C)88 g/mol
D)106 g/mol

Question

Quizplus · Accepted Answer

We can use the ideal gas law to solve for the moles of the gas:

PV = nRT

where P = 60 cm Hg = 0.79 atm (using the conversion factor 1 atm = 760 mm Hg), V = 125 mL = 0.125 L, T = 25°C = 298 K, and R = 0.0821 L atm/mol K.

n = (PV)/(RT) = (0.79 atm x 0.125 L)/(0.0821 L atm/mol K x 298 K) = 0.00486 mol

Then, we can use the definition of molar mass (mass/moles) to solve for the molar mass:

molar mass = mass/moles = 0.429 g/0.00486 mol = 88 g/mol

Therefore, the correct answer is D.

A 0429-G Sample of Gas Occupies 125 ML at 60