A fish swimming in water body when taken out from the water body is covered with a film of water of weight 36 g. When it is subjected to cooking at \(100^{\circ}\mathrm{C}\), then the internal energy for vaporization in \(\mathrm{kJ}\,\mathrm{mol}^{-1}\) is ______. [nearest integer] [Assume steam to be an ideal gas. Given \(\Delta_{\text{vap}}\mathrm{H}^{\ominus}\) for water at 373 K and 1 bar is \(41.1\,\mathrm{kJ}\,\mathrm{mol}^{-1}\); \(\mathrm{R}=8.31\,\mathrm{JK}^{-1}\,\mathrm{mol}^{-1}\)]

JEE Main · 2022 · 26 Jun 2022 · Shift 2 · Chemical Thermodynamics

A fish swimming in water body when taken out from the water body is covered with a film of water of weight 36 g. When it is subjected to cooking at

10 0^{\circ} C

, then the internal energy for vaporization in

kJ mol^{- 1}

is ______. [nearest integer]
[Assume steam to be an ideal gas. Given

Δ_{vap} H^{⊖}

for water at 373 K and 1 bar is

41.1 kJ mol^{- 1}

;

R = 8.31 JK^{- 1} mol^{- 1}

]

Answer: 38

For the vaporization process:

H_{2} O (l) \to H_{2} O (g)

The relationship between ΔH and ΔU is:

Δ U = Δ H - Δ n_{g} R T

where Δn_g = moles of gaseous products - moles of gaseous reactants = 1 - 0 = 1

Δ U = 41.1 - (1 \times 8.31 \times 373) /1000

Δ U = 41.1 - 3.1

Δ U = 38 kJ/mol

Answer = 38

JEE Main · 2022 · 26 Jun 2022 · Shift 2 · Integer answer