Question

At the same conditions of temperature and pressure, 5.0 dm^3 of a gas of molecular formula C_2 H_2, has a mass of 15 g, while 1.0 dm^3 of gas D has a mass of 1.4 g. What is the molar mass of gas D?

Underscore means subscript but I can't get the equation thingy to work. So it's meant to be C(subscript 2)H(subscript 2)

Answer 1

12 g/mol

Step-by-step explanation:

From Avogadro's law;

V1/n1 = V2/n2

V1 = 5.0 dm^3

n1 = 15 g/26 g/mol = 0.6 moles

V2 = 1.0 dm^3

n2 = ?

V1n2 = V2n1

n2 = V2n1/V1

n2 = 1 * 0.6/5

n2 = 0.12 moles

Molar mass= mass of gas D/number of moles of gas D

Molar mass= 1.4 g/0.12 moles

Molar mass= 12 g/mol