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MHT CET202618 April 2026Morning ShiftChemistryThermodynamics (C)Actual

Calculate H for the following reaction at 300 K 2 C _ (s) + 3 H _ 2(g) C ₂ H _ 6(g) if U for the reaction is -80 kJ ( R = 8.314 JK ⁻¹ mol ⁻¹ )

Options

  1. A-85.00 kJ
  2. B-43.00 kJ
  3. C-128.00 kJ
  4. D-170.00 kJ

Correct answer

A. -85.00 kJ

Step-by-step solution

The given reaction is 2 C _ (s) + 3 H _ 2(g) C ₂ H _ 6(g) Change in number of gaseous moles, n_g = n_ p(g) - n_ r(g) = 1 - 3 = -2 Given U = -80 kJ T = 300 K R = 8.314 J K ⁻¹ mol ⁻¹ = 8.314 10⁻³ kJ K ⁻¹ mol ⁻¹ Using the relation H = U + n_g RT H = -80 + (-2) 8.314 10⁻³ 300 H = -80 - 4.9884 H = -84.9884 kJ -85.00 kJ Answer: -85.00 kJ

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