Reactions involving energy changes:
Exothermic and Endothermic reactions.
Chemical reactions that:
 give out heat are called exothermic reactions.
 take in heat are called endothermic reactions.
In exothermic reactions the temperature of the reactants / products increases.
In endothermic reactions the temperature of the reactants / products decreases.
You have to investigate whether or not the following reactions are exothermic or endothermic.
1.
Sodium hydroxide - hydrochloric acid.
Measure out 25 mls of the sodium hydroxide using the measuring cylinder and pour into the
plastic cup.
Record the temperature.
Measure out 25 mls of the hydrochloric acid using the measuring cylinder and pour into the
plastic cup. Stir with the thermometer.
Temperature of the hydrochloric acid / sodium
hydroxide solution = ................... oC
Highest / lowest temperature reached =....... oC
Temperature change =................... oC
The reaction is
2.
EXOTHERMIC
ENDOTHERMIC
(Circle your choice)
Ethanoic acid - ammonium carbonate reaction
Measure out 25 mls of the ethanoic acid - using
the measuring cylinder and pour into the plastic
cup.
Record the temperature.
Add two heaped spatulas of ammonium
carbonate. Stir and note the temperature change.
Temperature of the ethanoic acid solution
=....................... oC
Highest / lowest temperature reached =....... oC
Temperature change =..................... oC
The reaction is
EXOTHERMIC
ENDOTHERMIC
(Circle your choice)
3.
Hydrochloric acid - magnesium reaction
Measure out 25 mls of the hydrochloric acid - using the
measuring cylinder and pour into the plastic cup.
Record the temperature.
Drop in a 10 cm length of magnesium ribbon and stir
with the thermometer.
Note the temperature change.
Temperature of the hydrochloric acid solution
=....... oC
Highest / lowest temperature reached =....... oC
=....... oC
Temperature change
The reaction is
4.
EXOTHERMIC
ENDOTHERMIC
(Circle your choice)
Sodium carbonate - zinc sulphate solution.
-
Measure out 25 mls of the sodium carbonate solution using the measuring cylinder and pour into the plastic
cup.
Record the temperature.
Add 25 mls of zinc sulphate solution.
Stir and note the
greatest temperature change.
Temperature of the sodium carbonate solution =....... oC
Highest / lowest temperature reached =....... oC
Temperature change =....... oC =
The reaction is
EXOTHERMIC
ENDOTHERMIC
(Circle your choice)
QUESTION
Which reaction is the most:
(i)
Exothermic ? .................................................................................................................
(ii)
Endothermic ? .................................................................................................................