Question

Henry s constant for argon is 40K bar in water, determine molal concentration of argon in water when it is stored above water at 10bar pressure

Answer 1

Hi dishaR,
Please find below the solution to the asked query:

According to Henry's Law: the partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas (x) in the solution by following relating: p = KH x

Hence, mole fraction of the gas in solution (x) = p / KH = 10 bar / 40,000 bar = 2.5 x 10-4

As 1 litre of water contains 55.5 mol of it, then if n represents number of moles of argon in solution:

xargon=n moln mol + 55.5 mol=2.5×10−4⇒n mol55.5 mol =2.5×10−4 [n in the denominator can be neglected as n <<55.5 mol]⇒Thus, n=2.5×10−4×55.5=1.39×10−2 mol

Hence, the molal concentration of argon in water = 1.39 x 10-2 m