Calculate the amount of heat that must be released to convert 20.0 g of mercury vapor at #387^@"C"# to liquid mercury at #307^@"C"# (in kJ)?
Heat added or removed from a substance when there is a change of temperature without a change in phase (
However, we need to appreciate the underlying steps in the thermal transformation taking place. The change takes place in 3 steps:
- Extraction of heat to lower temperature of vapour from
#387^o C#to #357^o C#(phase transition temperature).
- Phase transition from vapour to liquid without change in temperature ( Heat added/removed = Heat of phase transition/unit mass * mass of substance )
- Extraction of heat to lower temperature of liquid from
#357^o C#to #307^o C#.
Total heat removed =