For the solubility of gases in liquid, the correct statement at high temperature is:
A. Solubility of gases increase
B. Value of Henry's constant \((k_H)\) increases
C. Solubility of gases decrease
D. Value of \(k_H\) decreases
E. Value of \(k_H\) does not change
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → B and C only
By Henry’s law, the partial pressure of a gas over a solution is proportional to its mole fraction in the solution: p = KH x. The higher the value of KH at a given pressure, the lower the solubility of the gas. Dissolution of a gas is exothermic, so on heating the gas escapes from the solution: KH values (for \( \ce{N2} \), \( \ce{O2} \) and other gases) increase with temperature, and the solubility of gases decreases.
A. Solubility of gases increase — Incorrect. Solubility of gases decreases as temperature rises; this is why aquatic animals are more comfortable in cold water.
B. Value of Henry’s constant (kH) increases — Correct. KH of \( \ce{N2} \) and \( \ce{O2} \) rises from 293 K to 303 K (table below).
C. Solubility of gases decrease — Correct. A higher KH means a lower mole fraction of dissolved gas at the same pressure.
D. Value of kH decreases — Incorrect. KH rises with temperature.
E. Value of kH does not change — Incorrect. KH depends on temperature (and on the nature of the gas).
NCERT (2026-27 edition):
Solubility of a Gas in a Liquid – …
Table 1.2: Values of Henry’s Law Constant for Some Selected Gases in Water (rows)
| Gas | Temperature/K | KH/kbar |
|---|---|---|
| N2 | 293 | 76.48 |
| N2 | 303 | 88.84 |
| O2 | 293 | 34.86 |
| O2 | 303 | 46.82 |