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Measuring enthalpy change of combustions
Please someone help!
When measuring the enthalpy change of combustions of different alcohols, why do we need to increase the temperature of the water by around 15-25 degrees?? Why 15 degrees? Why not 5? Why 25 degrees? Why not higher?
When measuring the enthalpy change of combustions of different alcohols, why do we need to increase the temperature of the water by around 15-25 degrees?? Why 15 degrees? Why not 5? Why 25 degrees? Why not higher?
you need a decent temperature rise to minimise percentage errors. If the error in each thermometer reading is 0.25ºC then for a temperature rise of 5º the percentage error is 0.5/5 x 100 = 10%. This is clearly too great.
If the temperature rise is too large, however, you are starting to introduce problems of cooling due to CC&R and also evaporation of the water carrying off energy and changing the mass.
If the temperature rise is too large, however, you are starting to introduce problems of cooling due to CC&R and also evaporation of the water carrying off energy and changing the mass.
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