Question

An experiment shows that a 115 mLmL gas sample has a mass of 0.169 gg at a pressure of 700 mmHgmmHg and a temperature of 30 ∘C∘C. What is the molar mass of the gas?

Answer 1

39.7g/mol

Step-by-step explanation:

To calculate the molar mass of the gas, first let us calculate the number of mole of the gas. This is illustrated below:

Data obtained from the question include:

V = 115mL = 0.115L

P = 700mmHg

Recall: 760mmHg = 1atm

700mmHg = 700/760 = 0.92atm

T = 30°C = 30 +273 = 303K

R = 0.082atm.L/Kmol

n =?

PV = nRT

n = PV/RT

n = (0.92 x 0.115)/(0.082x303)

n = 4.26x10^-3mol

Now we can obtain the molar mass of the gas as follows:

Mass of the gas = 0.169g

Number of mole of the gas = 4.26x10^-3mol

Molar Mass of gas =?

Number of mole = Mass /Molar Mass

Molar Mass = Mass/number of mole

Molar Mass of the gas = 0.169/4.26x10^-3

Molar Mass of the gas = 39.7g/mol