Rates of
Reaction Catalysts and
Energy Search Questions 
Energy - Examples of Endothermic and Exothermic Reactions.
Most reactions are exothermic. Examples are
1) Combustion of methane (natural gas).
2) Neutralisation.
3) Adding concentrated sulfuric acid to water is
highly
exothermic (gives out a
lot of heat).
4) Adding water to anhydrous
copper(II) sulfate is
exothermic.
Anhydrous copper(II)
sulfate is white.
Anhydrous is pronounced "an-high-drus"
Anhydrous means "without water".
Anhydrous copper(II)
sulfate is copper(II)
sulfate which is
completely dry. When water is added to it, it turns
into the
familiar hydrated
blue crystals.
Hydrated is pronounced "high-dray-tid", it means
'with water'.
This is used as a test for water.
If blue (hydrated)
copper(II) sulfate crystals
are heated,
an endothermic reaction occurs, they
lose their water,
turn white and become
anhydrous
copper(II) sulfate crystals
again.
The reaction is reversible.
Blue copper(II)
sulfate crystals will also turn
white
in the presence of concentrated sulfuric acid.
Exothermic reactions can be used for self-heating cans.
Few reactions are endothermic. Examples are
1) Photosynthesis.
Chlorophyll is a very clever catalyst,
which allows plants to make
sugar from carbon dioxide in the air.
The energy needed for the reaction comes from sunlight.
3) The reaction of ethanoic acid with sodium carbonate.
4) Dissolving some salts in water is
an endothermic process.
Potassium chloride and ammonium nitrate
both take in energy when they dissolve. If you put
a thermometer in the
solution as they are dissolving,
you will see that the temperature
drops.
5) Melting, boiling and evaporation
are all endothermic processes (not reactions).
Endothermic reactions can be used for injury packs in sports.
Rates of
Reaction Catalysts and
Energy Search Questions
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