A given mass of the gas occupies 919ml in dry state at STP The same mass when collected over - Chemistry - States of matter

Question

A given mass of the gas occupies 919ml in dry state at STP The
same mass when collected over water at 15 degree celsius and 750 mm
pressure occupies 1 litre volume Calculate the vapour pressure of
water at 15 degree celsius

Shikha Aggarwal · Accepted Answer

We know,
PDry 
gas=
PTotal -
Pwater 
vapour

We are provided
with (at STP) :
V1 =
919 mL V2=
1000 mL
P1 =
760 mm Hg P2=
? (dry gas)
T1 =
273 K T2=
273+15 =288 K
PTotal = 750 mmHg

by
applying gas equation :

P1V1T1=P2V2T2760×919273=P2×1000288⇒P2 = 736 82 mm
Hg

â€‹PDry 
gas=
PTotal -
Pwater 
vapour

Pwater 
vap=
750- 736 82 = 13 18 mm of Hg

A given mass of the gas occupies 919ml in dry state at STP. The same mass when collected over water at 15 degree celsius and 750 mm pressure occupies 1 litre volume. Calculate the vapour pressure of water at 15 degree celsius.