Arrange the following gases in the increasing order of their solubility in water at 298 K and atmospheric pressure.
(A) $CH_4 (K_H = 0.413\, kbar)$
(B) $HCHO (K_H = 1.83 × 10^{-5}\, kbar)$
(C) $He (K_H = 144.97\, kbar)$
(D) $CO_2 (K_H = 1.67\, kbar)$
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (C), (D), (A), (B)
The solubility of a gas in water is inversely proportional to its Henry’s law constant ($K_H$):
$\text{Higher } K_H ⇒\text{lower solubility}$
Given $K_H$ values (in kbar):
- CH₄ → 0.413
- HCHO → 1.83 × 10-5
- He → 144.97
- CO₂ → 1.67
Now arrange increasing solubility (lowest solubility → highest solubility):
- He ($K_H$ = 144.97) → least soluble
- CO₂ ($K_H$ = 1.67) → more soluble
- CH₄ ($K_H$ = 0.413) → even more soluble
- HCHO ($K_H$ = 1.83 × 10-5) → most soluble
Correct order (increasing solubility): (C), (D), (A), (B)