Question

A 0.334 g sample of an unknown halogen occupies 109 mL at 398 K and 1.41 atm. What is the identity of the halogen?

Answer 1

Assuming ideal conditions, we know that.

PV = nRT

where,

P = Pressure

V = Volume

n = number of moles

R = gas constant = 0.0821

T = Temperature

Given,

P = 1.41 atm

V = 109 mL = 0.109 L

T = 398 K

Using PV = nRT we get,

1.41 x 0.109 = n x 0.0821 x 398

=> n = 4.7035 x 10^-3 moles

We know that,

Mass = Moles x Molar Mass

=> 0.334 = 4.7035 x 10^-3 x Molar Mass

=> Molar Mass = 71 g / mol

We know that molar mass of Cl2 si 71 g / mol (approx)

=> The halogen is Cl2 (Chlorine)