Solutions Question 396

Question: At $ 20{}^\circ C $ and 1.00 atm partial pressure of hydrogen, 18 mL of hydrogen, measured at STP, dissolves in 1L of water. If water at $ 20{}^\circ C $ is exposed to a gaseous mixture having a total pressure of 1400 Torr (excluding the vapour pressure of water) and containing 68.5% $ H_2 $ by volume, find the volume of $ H_2, $ measured at STP, which will dissolve in 1L of water.

Options:

A) 18 mL

B) 12 mL

C) 23 mL

D) 121 mL

Show Answer

Answer:

Correct Answer: C

Solution:

$ p(H_2)=(1400Torr)(0.685) $

$ =959Torr\equiv 959/760atm=1.26atm $

According to Henry’s law

Amount of gas absorbed is directly proportional to pressure.

Hence $ \frac{V}{18mL}=\frac{1.26atm}{1atm} $
$ V=23mL $



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