Consider a solution of CO2(g) dissolved in water in a closed container. Which one of the following plots correctly represents variation of log (partial pressure of CO2 in vapour phase above water) [y-axis] with log (mole fraction of CO2 in water) [x-axis] at 25 ?
- [figure]
- [figure]
- [figure]
- [figure]
Answer
(3) [figure]
Solution
Henry's law: pCO2 = KH xCO2
pCO2 = xCO2 + KH
Comparing with y = mx + c: slope = 1 (a rising straight line) and intercept = KH.
For CO2 in water at 298 K, KH = 1.67 108 Pa (NCERT) KH is positive.
The plot is a straight line of positive slope with a positive intercept on the y-axis.
Answer: (3)