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on which portions of this graph is the amount of heat removed related primarily

ID: 980786 • Letter: O

Question

on which portions of this graph is the amount of heat removed related primarily to a lowering of the potential energy in the molecule Sllger Hydrögen bonds than Ho. Never- theless, HF has a lower boiling point than H,O. Explain why this is so. Energy and Changes of State 11.50 The following is a cooling curve for one mole of a substance: Heat removed (a) On which portions of this graph do we find the average kinetic energy of the molecules of the sub- stance changing? (b) On which portions of this graph is the amount of heat removed related primarily to a lowering of the potential energy of the molecules? (c) Which portion of the graph corresponds to the release of the heat of vaporization?

Explanation / Answer

(a) Average kinetic energy is directly associated to the temperature. Hence whenever the temperature changes average kinetic energy changes.

Answer : 1,3 and 5

(b) Answer : 4

In this region, the energy being lost is reflected by decreases in the potential energy of the substance due to crystallisation.

(c) Region 2 corresponds to the release of heat of vaporisation, to the left of which the substance exists as gas.