Question

Calculate the molar mass of a gas if 0.55g of gas occupies 0.200L at 0.968 atm and 298K
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Answer 1

Answer:

PV = nRT

n = number of moles = (mass)/(molecular weight) = m/W

m = 0.550 g = 5.5 x 10-4 kg

R = universal gas constant = 8.31 J / (mol K)

W = molecular weight = ?

V = 0.2 L = 0.2 * 1000 cm3 = 0.2 * 1000 * 10-6 m3 = 2 x 10-4 m3

P = 0.968 atm = 0.968(101325 Pa) = 98083 Pa

T = 289K

PV = nRT = (m/W)RT

W = mRT / PV = (5.5 x 10-4 kg)[8.31 J/(mol K)](289 K) / [(98083 Pa)(2 x 10-4 m3)]

W = 0.067335 kg/mol = 67.335 g/mol

Explanation:

hope you better understand ..

Answer 2

We have to calculate the molar mass of a gas if 0.55 g of the gas occupies 0.2 L at 0.968 atm and 298 K.

solution : temperature of the gas, T = 298 K

volume of the gas, V = 0.2 L

pressure of the gas, P = 0.968 atm

let the molar mass of the gas is M,

then no of moles of the gas, n = mass of gas/molar mass of gas

= 0.55/M

now using gas equation, PV = nRT

⇒ 0.968 atm × 0.2 L = 0.55/M × 0.082 atm. L/mol/K × 298K

⇒ M = (0.55 × 0.082 × 298)/(0.968 × 0.2) = 69.42 g/mol

therefore the molar mass of the gas is 69.42 g/mol