2. An evacuated glass vessel weighs 50 gm. when empty, 148.0g when com

1.	2. An evacuated glass vessel weighs 50 gm. when empty, 148.0g when completely filled with liquid of density 0.98g m and50.5g when filled with an ideal gas at 760mm at 300 K. Determine the molecular weight of the gas. [IIT-JEE 1998]
Answer» Weight of liquid = 148 – 50 =98 g Volume of liquid = 98/0.98 = 100 ml = volume of vessel it means, vessel of 100 ml contain ideal gas at 760 mm Hg at 300 K Weight of gas = 50.5 - 50 = 0.5g Using, PV = nRT = w/m RT 760/760 * 100/1000 = 0.5/m * 0.082 *300 [n = 0.5/m] ∴ Molecular weight of gas (m) =123

2. An evacuated glass vessel weighs 50 gm. when empty, 148.0g when completely filled with liquid of density 0.98g m and50.5g when filled with an ideal gas at 760mm at 300 K. Determine the molecular weight of the gas. [IIT-JEE 1998]

Answer»

Weight of liquid = 148 – 50 =98 g

Volume of liquid = 98/0.98 = 100 ml = volume of vessel it means, vessel of 100 ml contain ideal gas at 760 mm Hg at 300 K

Weight of gas = 50.5 - 50 = 0.5g

Using, PV = nRT = w/m RT

760/760 * 100/1000 = 0.5/m * 0.082 *300 [n = 0.5/m]

∴ Molecular weight of gas (m) =123