The mass of 94.5 ml of a gas at STP is found to be 0.2231 g . calculat

1.	The mass of 94.5 ml of a gas at STP is found to be 0.2231 g . calculate its molecular mass
Answer» Let MOLECULAR mass of gas is M g/MOL. given, mass of gas at STP [ standard temperature and PRESSURE ] = 0.2231g so, NUMBER of mole of gas, n = 0.2231/M VOLUME of gas, V = 94.5 ml at STP, temperature , T = 273.15K pressure , P = 1atm from gas equation, PV = nRT or, 1atm × 94.5 ml = (0.2231/M)mol × 0.082 atm.L/mol.K × 273.15K or, 1atm × 94.5 × 10^-3 litre = (0.2231/M)mol × 0.082 atm.L/mol.K × 273.15K or, M = 0.2231 × 0.082 × 273.15/(94.5 × 10^-3) = 52.87 g/mol hence, molar mass of gas = 52.87 g/mol

The mass of 94.5 ml of a gas at STP is found to be 0.2231 g . calculate its molecular mass

Answer»

Let MOLECULAR mass of gas is M g/MOL.

given, mass of gas at STP [ standard temperature and PRESSURE ] = 0.2231g

so, NUMBER of mole of gas, n = 0.2231/M

VOLUME of gas, V = 94.5 ml

at STP,

temperature , T = 273.15K

pressure , P = 1atm

from gas equation,

PV = nRT

or, 1atm × 94.5 ml = (0.2231/M)mol × 0.082 atm.L/mol.K × 273.15K

or, 1atm × 94.5 × 10^-3 litre = (0.2231/M)mol × 0.082 atm.L/mol.K × 273.15K

or, M = 0.2231 × 0.082 × 273.15/(94.5 × 10^-3)

= 52.87 g/mol

hence, molar mass of gas = 52.87 g/mol