Question

Argon, a noble gas, partitions from the atmosphere into water. a) Write out the mass action reaction and associated equilibrium expression for Arg) dissolution in water. (4 marks) b) Using the information provided in Table 1, calculate the dimensionless Henry's constant (KH) for Ar at 25°C and 1 atm. (4 marks) Species AG, (kJ mol') Aria) Ara) 8.36

Answer 1

Part a).

Mass action reaction: Ar(g) + H₂O(l) = Ar(aq)

Equilibrium expression: K = [Ar(aq)]/[Ar(g)]

Part b).

$\Delta$ G_f^o = -RT ln(K_H)

i.e. 8.36*1000 J/mol = -8.314 J/mol.K * (25+273.15) K * ln(K_H)

i.e. ln(K_H) = -3.3726

i.e. K_H = e^-3.3726 = 0.0343 or 3.43*10^-2