C5-Energy changes Flashcards
1
Q
exothermic
A
an increase of temperature in a reaction
2
Q
endothermic
A
an decrease of temperature in a reaction
3
Q
examples of exothermic reactions
A
combustion,respiration,neutralisation
4
Q
examples of endothermic reactions
A
thermal decomposition-ice packs
5
Q
activation energy
A
minimum amount of energy required for a chemical reaction to take place
6
Q
catalyst
A
increase rate of reaction
7
Q
required practical- temperature changes in reacting solutions
A
- place polystyrene cup inside beaker.prevents cup from falling.
- using measuring cylinder,measure 30cm3 of the acid (hydrochloric).Pour this into polystyrene cup
- record temperature of the acid using a thermometer
- use on strip of magnesium
5.add the magnesium to the acid and record the temperature.Do this every minute for 10 mins.
8
Q
bond making/breaking in endothermic reaction
A
energy is needed to break chemical bonds-energy change is positive
9
Q
bond making/breaking in exothermic reaction
A
energy is needed to form chemical bonds-energy change is negative
