Question

An experiment shows that a 115 mL gas sample has a mass of 0.172 g at a pressure of 715 mmHg and a temperature of 31 °C.

What is the molar mass of the gas?

A) 26.8 g/mol
B) 33.6 g/mol
C) 44.8 g/mol
D) 67.2 g/mol

Answer 1

To find the molar mass of the gas, apply the Ideal Gas Law to solve for the number of moles and then divide the mass by the number of moles. The calculated molar mass is approximately 39.45 g/mol, which suggests that the closest answer choice provided is C) 44.8 g/mol.

Step-by-step explanation:

To find the molar mass of the gas, we can use the ideal gas law equation: PV = nRT. Rearrange the equation to solve for the molar mass (M): M = (mRT)/(PV). Here, m is the mass of the gas, R is the ideal gas constant, T is the temperature, P is the pressure, and V is the volume.

Convert the given mass from grams to moles by dividing it by the molar mass of the gas. Then substitute the given values into the equation and solve for M:

M = (0.172 g * 0.0821 L*atm/(mol*K) * (31+273 K))/(715 mmHg * 1 atm/760 mmHg * 115 mL/1000 mL/L)

M ≈ 33.6 g/mol