Energy changes
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In enthalpy reactions why do we take several readings and not just the initial and final reading?
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Corrie writes .....
You could just take the initial and final temperature readings, but the final reading is likely to contain an error as a result of loss of heat to the surroundings if the mixture warmed up, or gain of heat if it cooled down, during the time for the reaction to complete. By taking readings for several minutes after mixing and plotting the temperature vs time graph, you will see the mixture slowly cooling down (or warming up) after the reaction is over.
By extrapolating the curve back to the time of mixing, the maximum temperature rise (or fall) before any heat loss (or gain) to the surroundings can be found, giving a more accurate value of the temperature change solely due to reaction.
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updated: 14 April 2008
