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MHT CET · Chemistry · Thermodynamics (C)

Calculate the enthalpy of vaporisation of ethanol if 11.5 g of ethanol is completely vaporised by supplying 11.8 kJ of heat.

  1. A \(21 \cdot 7 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
  2. B \(47.2 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
  3. C \(65 \cdot 1 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
  4. D \(39.0 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(47.2 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

Step-by-step Solution

Detailed explanation

\(n = \frac{11.5 \mathrm{~g}}{46.0 \mathrm{~g} \mathrm{~mol}^{-1}} = 0.250 \mathrm{~mol}\) \(\Delta H_{vap} = \frac{11.8 \mathrm{~kJ}}{0.250 \mathrm{~mol}} = 47.2 \mathrm{~kJ} \mathrm{~mol}^{-1}\)