The student's evaluation of an experiment is given below.
" my calculated value of the enthalpy of combustion was numerically much less than the data book value. The reasons for my low value include;
1) Heat losses to the surrounding air;
2) when I rechecked the mass of the spirit lamp and ethanol after combustion. I noticed that it had lost mass even when it was not being used;
3) a black solid which formed on the base of the beaker.
i) explain why the spirit lamp and ethanol lost mass even when not in use.
Am I missing the point by saying;
the liquid alcohol is burnt, therefore evaporates producing a gas which is lost, so the mass decreases???
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Chem 3B Jan 04 question. watch
- Thread Starter
- 11-05-2005 20:24
Offline17ReputationRep:Community AssistantStudy Helper
- Community Assistant
- Study Helper
- 11-05-2005 20:41
yes, it says "even when not in use" therefore it isn't burning...
however you are correct in that the reason is evaporation of the volatile spirits in the burner..