JEE Main · 2020 · Shift-ImediumSOL-069

Henry's constant (in kbar) for four gases , , and in water at 298 K is given below: | | | | | | |---|---|---|---|---| |…

Solutions · Class 12 · JEE Main Previous Year Question

Question

Henry's constant (in kbar) for four gases α\alpha, β\beta, γ\gamma and δ\delta in water at 298 K is given below:

| | α\alpha | β\beta | γ\gamma | δ\delta | |---|---|---|---|---| | KHK_H | 50 | 2 | 2×1052 \times 10^{-5} | 0.5 |

(density of water = 10310^3 kg m⁻³ at 298 K)

This table implies that:

Options
  1. a

    α\alpha has the highest solubility in water at a given pressure

  2. b

    solubility of γ\gamma at 308 K is lower than at 298 K

  3. c

    The pressure of a 55.5 molal solution of δ\delta is 250 bar

  4. d

    The pressure of 55.5 molal solution of γ\gamma is 1 bar.

Correct Answerd

The pressure of 55.5 molal solution of γ\gamma is 1 bar.

Detailed Solution

Strategy:\n> Henry's law constant (KHK_H) inversely relates to solubility. For a given pressure, the gas with the lowest KHK_H will have the highest mole fraction (solubility). We also check the pressure for a 55.5 molal solution (which means x=0.5x = 0.5).\n\nStep 1: Evaluate Statement (3)\nThe statement mentions a 55.5 molal solution of δ\delta.\n- 55.5 mol of solute per 1 kg (55.5 mol) of water.\n- Mole fraction x=frac55.555.5+55.5=0.5x = \\frac{55.5}{55.5 + 55.5} = 0.5.\nUsing Henry's law p=KHxp = K_H \cdot x for δ\delta (KH=0.5textkbarK_H = 0.5\\text{ kbar}):\np=0.5textkbartimes0.5=0.25textkbar=250textbarp = 0.5\\text{ kbar} \\times 0.5 = 0.25\\text{ kbar} = 250\\text{ bar}\nThis matches statement (3) exactly.\n\nStep 2: Determine why other statements are incorrect\n- (a): α\alpha has the highest KHK_H (50 kbar), which means it has the lowest solubility.\n- (d): For γ\gamma, KH=2times105textkbarK_H = 2 \\times 10^{-5}\\text{ kbar}. At x=0.5x=0.5:\n p=(2times105)times0.5=105textkbar=0.001textbar1textbarp = (2 \\times 10^{-5}) \\times 0.5 = 10^{-5}\\text{ kbar} = 0.001\\text{ bar} \neq 1\\text{ bar}.\n\ntextAnswer:(3)\boxed{\\text{Answer: (3)}}

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Solutions) inside The Crucible, our adaptive practice platform.