Question

An evacuated glass vessel weighs 40 g when empty, 135 g when filled with a liquid of density 0.95 g mL⁻¹ and 40.5 g when filled with an ideal gas at 0.82 atm at 250 K. The molar mass of the gas in g mol⁻¹ is ______.

(Given: R = 0.082 L atm K⁻¹ mol⁻¹)

पर्याय

• 35

• 50

• 75

• 125

Answer 1

An evacuated glass vessel weighs 40 g when empty, 135 g when filled with a liquid of density 0.95 g mL⁻¹ and 40.5 g when filled with an ideal gas at 0.82 atm at 250 K. The molar mass of the gas in g mol⁻¹ is 125.

Explanation:

Mass of liquid = 135 − 40 = 95 g

Volume of liquid = `"mass"/"density"`

= `95/0.95` mL

= 100 mL

= 0.1 L

Mass of ideal gas = 40.5 g − 40 g = 0.5 g

PV = nRT

`0.82 xx 0.1 = (0.5/"M") xx 0.082 xx 250`

⇒ M = 125