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Acids and Alkalis

Titration - Amount of Heat.

The end point of a titration can be found
by measuring the amount of heat released into the solution.

The reaction between an acid and an alkali is exothermic.
If a thermometer is placed in the solution in the conical flask
the temperature will be seen to increase when acid is added to the alkali.
At neutralisation the amount of heat released will decrease
because there are no more hydroxide ions left
for the hydrogen ions to react with. 

If you draw a graph of temperature against the amount of acid added
you can see where the
end point is.

The End Point for Titration using Temperature

The titration can be repeated
with the same amounts of acid and alkali used at the end point.
Pure salt crystals can then be crystallised from the neutral solution.

This is the least accurate of the 3 methods because heat is lost
from the conical flask to the environment during the titration.
It may not be
very obvious where the end point occurs.

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