Question

A certain quantity of a gas occupies 100ml
when collected over water at 15°C and 750mm
pressure. If it occupies 91.9ml in dry state at
STP, the vapour pressure of water at 15°C is
1) 12.8mm
2) 14.8mm
3) 13.2mm
4) 13.7mm​

Answer 1

Answer:

Option 3)13.2

Explanation:

Let the vapour pressure be p

Then,

P1(dry gas) =(750-p)mm

V1=100ml

T1=288K

At STP conditions,

P2=760mm

V2=91.9ml

T2=273K

By applying gas equation,

(750-p)*100/288=760*91.9/273

Which will give the answer as

p=13.184176

Approx 13.2.Hope it helps