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Heat needed to vaporise a given mass of a liquid from its molar enthalpy of vaporisation

This type of question, asked 2 times: 29 Jun 2022, 29 Jan 2024. All 2 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    29 Jun 2022

    52
     17.0 g\ 17.0\text{ }g of NH3NH_{3} completely vapourises at −33.42∘C-33.42^{\circ}C and 1 bar pressure and the enthalpy change in the process is 23.4 kJ mol−123.4\text{ }kJ{\text{ }mol}^{- 1}. The enthalpy change for the vapourisation of 85 g85\text{ }g of NH3NH_{3} under the same conditions is ____\_\_\_\_ kJkJ.

  2. Question 2

    29 Jan 2024

    148
    Standard enthalpy of vapourisation for CCl4CCl_{4} is 30.5 kJ mol−130.5\text{ }kJ{\text{ }mol}^{- 1}. Heat required for vapourisation of 284 g284\text{ }g of CCl4CCl_{4} at constant temperature is ____ kJkJ. (Given molar mass in mol−1;C=12,Cl=35.5mol^{- 1};C = 12,Cl = 35.5 )