A sample of oxygen is collected in a 175 mL container over water at 15°C, and the barometer reads 752.0 torr. What volume would the dry gas occupy at 770.0 torr and 15°C? (Water vapor pressure at 15°C is 12.8 torr.)

The volume of dry gas = 168 L

Given

175 ml container at 15°C

P total = 752 torr

water vapour = 12.8 torr

Required

The volume of dry gas

Solution

Dalton's law of partial pressure :

P tot = P₁ + P₂ + P₃  

P total = P O2 + P water

P O2 = 752 - 12.8

P O2 = 739.2 torr

Boyle's Law  

At a fixed temperature, the gas volume is inversely proportional to the pressure applied  

P₁V₁ = P₂V₂

739.2 175 = 770 .V₂

V₂ = 168 L

the formula for the conversion of temperature from degree celsius to kelvin is:

the sample of water at is converted to kelvin temperature by using the above formula as:

on comparing the two samples of water at or we can say that at and at respectively. the difference between the temperatures of two samples of water is:

hence, one can say that the sample of water at is greater than the sample of water at by .