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)?
1 Answer
Jun 6, 2015
Heat added or removed from a substance when there is a change of temperature without a change in phase (
where
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 to357^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 to307^o C .
Step I:
Step II:
Step III:
Total heat removed =