Question

2.8 L of unknown gas X2 under STP weighs 5g. atomic mass of X

Answer 1

Solution:

Given,

2.8 L of X2 gas under STP = 5g

We need to find,

Atomic mass of X

We know that

Any gas occupies a volume of 22.4L at STP( 1 mole)

2.8 L of X2 = ? moles

22.4L of X2 = 1 mole

Cross multiplying we have

→ 2.8 × 1 = ? × 22.4

→ 2.8/22.4 = ?

→ ? = 0.125

Hence , no. of moles of X2 gas = 0.125 moles

Here,

No. of moles = given mass/actual mass

♦ 0.125 = 5g/actual mass

♦ 5/0.125 = actual mass of X2

♦ Actual mass of X2 = 40

♦ Actual mass of X = 20g

Hence , atomic mass of X = 20g