Question

At 25 °C and 775 Torr, carbon dioxide has a solubility of 0.0347 M in water. What is its solubility at 25 °C and 1850 Torr?

Answer 1

This problem is solved using Henry's Law, where the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid:

C = k P_gas

where

• C is the solubility of a gas at a fixed temperature in a particular solvent (in units of M).
• k is Henry's law constant (often in units of M/atm)
• P_gas is the partial pressure of the gas (often in units of Atm)

Then, if at T = 25°C we have that:

P = 775 torr ( 1 atm / 760 torr ) = 1.01974 atm

C = 0.0347 M

we can know k:

k = C / P

k = 0.0347 M / 1.01974 atm = 0.034 M / atm

Knowing the value of k, we can know C when P = 1850 torr

P = 1850 torr ( 1 atm / 760 torr ) = 2.434 atm

C = k P

C = ( 0.034 M / atm ) ( 2.434 atm ) = 0.0827 M