Question

The Henry's law constant for helium gas in water at 30°C is 3.70 x10^-4 M/atm. If the partial pressure of helium above a sample of water is o.650 atm, what is the concentration of helium in water? 

A. 5.69 x10^-4 M B. 1.76 10³ M C. 1.30 M vD. 2.41 x10^-4 M

Answer 1

henry's law constant k_H = 3.70 x 10^-4 M / atm

partial pressure of He = 0.650 atm

concentration = k_H x P

                      = 3.70 x 10^-4 x 0.650

                      = 2.41 x 10^-4 M

concentration = 2.41 x 10^-4 M

Answer 2

   According to Henry's law

      Molar concentration, c = k .p

k - Henry's law constant = 3.70x10^-4 M/atm

p - pressure of gas over solution = 0.650 atm

c = 3.7 x 10^-4 x 0.650

     = 2.405 x 10^-4 M