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Acids and Alkalis

Using the Amount of Heat to find the End Point of a Titration.

The end point 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 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
you can see where the end point is.

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 4 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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