One mole of acetone requires less heat to vaporise than 1 mol of water. Which of the two liquids has a higher enthalpy of vapourisation?
o Enthalpy of vapourisation is defined as the heat consumed by a liquid to transform into the gaseous form at a certain pressure and temperature.
o 1 mole of acetone requires less heat than 1 mole of water to vaporize. So, water consumes less heat than the same amount of acetone for vapourisation.
Hence, amongst the two liquids, water has a higher enthalpy of vapourisation (consuming higher heat energy).
Therefore, ∆Hvapourisation (water) > ∆Hvapourisation (acetone).
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The reaction of cyanamide, NH2CN (s), with dioxygen was carried out in a bomb calorimeter, and DU was found to be –742.7 kJ mol–1 at 298 K. Calculate enthalpy change for the reaction at 298 K.
NCERT - Chemistry Part-I