Question

The concentration of dissolved CO2 gas in seawater is 5.00 x 10^–3 mol L–1 . The Henry’s law constant for CO2 at 298 K is 3.13 x 10^–7 mol L–1 Pa–1 . Calculate the partial pressure of carbon dioxide gas in the atmosphere above the ocean.

(A) 16.0 kPa

(B) 6.30 x 10–5 Pa

(C) 1.57 x 10–9 Pa

(D) 6.30 x 108 kPa

Answer 1

Amount of CO₂ Dissolved in seawater is liked to the Henry 's law ;  

[CO₂ (aq) ] = K_CO2  * P_CO2

(K_CO2  = Henry constant for CO₂ =3.13 x 10^–7 mol L–1 Pa–1 )

  P_CO2 = partial pressure of CO₂ in atmosphere above atmosphere = ?

[CO₂ (aq) ] = concentration of CO₂ in seawater = 5.00 x 10^–3 mol L^–1

P_CO2 = [CO₂ (aq) ] /  K_CO2   =  5.00 x 10^–3 mol L^–1 /  3.13 x 10^–7 mol L^–1 Pa^–1

P_CO2 = 15974 Pa ~ 16.0 K Pa (1000 Pa = 1 k Pa )

So, correct answer is  (A) 16.0 kPa.