Question

14.A 4.25 gram sample of an unknown gas is found to occupy a volume of 1.70 L at a pressure of 883 mm Hg and a temperature of 58 °C. The molar mass of the unknown gas is ______

g/mol.

Answer 1

58.5g/mol

Step-by-step explanation:

Given parameters:

Mass of gas = 4.25g

Volume = 1.7L

Pressure = 883mmHg

760mmHg = 1 atm

883mmHg =
`(883)/(760)` = 1.16atm

Temperature = 58°C = 58 + 273 = 331K

Unknown:

Molar mass of sample = ?

Solution:

To solve this problem, we use the ideal gas equation to find the number of moles;

PV = nRT

P is the pressure

V is the volume

n is the number of moles

R is the gas constant = 0.082atmdm³mol⁻¹K⁻¹

T is the temperature

n =
`(PV)/(RT)` =
`(1.16 x 1.7)/(0.082 x 331)` = 0.07mole

Since;

mass = number of moles x molar mass

4.25 = 0.07 x molar mass

Molar mass = 58.5g/mol