Consider a solution of CO_2 (g ) dissolved in water in a closed container. Which one of the following plots correctly represents variation of log (partial pressure of CO_2 in vapour phase above water…

Question

Consider a solution of CO_2 (g ) dissolved in water in a closed container. Which one of the following plots correctly represents variation of log (partial pressure of CO_2 in vapour phase above water) [y-axis] with log (mole fraction of CO_2 in water) [x-axis ] at 25^ C ?

Accepted Answer

Correct answer: B. (b) According to Henry's Law, the partial pressure of a gas in the vapour phase (p ) is proportional to the mole fraction of the gas in the solution (x ). The mathematical expression is: p=K_H x where K_H is the Henry's law constant. Taking logarithm on both sides: log (p )= log(K_H x) log (p )= log (K_H )+ log (x ) Comparing this with the equation of a straight line y= mx+c : y= log ⁡ (p ) (y-axis) x= log ⁡ (x ) (x-axis) m=1 (slope) c= log ⁡ (K_H ) (y-intercept) Since K_H for CO_2 in water is a positive constant at 25^ C , log ⁡ (K_H ) will be a constant intercept. The plot of log ⁡ (p ) vs log ⁡ (x ) is a straight line with a positive slope and a positive y -intercept. This corresponds to graph (b).

$Consider a solution of dissolved in water in a closed container. Which one of the following plots correctly represents variation of (partial pressure of in vapour phase above water) -axis] with (mole fraction of in water) -axis at ?$

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