Which reaction is most likely to make the temperature of the reaction mixture increase?
Question 1 Report
Which reaction is most likely to make the temperature of the reaction mixture increase?
Answer Details
Neutralisation of an acid by an alkali releases energy to the surroundings, so the mixture warms up. The reaction is the joining of hydrogen ions and hydroxide ions to make water:
H+(aq) + OH-(aq) → H2O(l)
Forming the strong O-H bonds in water gives out more energy than is needed to separate the ions, so \(\Delta H\) is negative and the temperature rises.
The other changes all absorb energy. Dissolving ammonium nitrate cools the water, which is why it is used in cold packs. Melting a solid needs energy to separate the particles, and thermal decomposition of a carbonate continues only while heat is supplied.
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