Exothermic and Endothermic Changes
Look at the picture of an Exothermic change. Use it
to help you explain what is happening.
During Exothermic changes,
_________ energy is transferred
from the ________________to the
_____________________
Fill in the blanks below with the correct words from
the word bank below.
1. In a chemical reaction the substances that you
react together are called ____________ and
the substances that form are called
____________.
2.
In ___________ reactions, energy is
_________ to the surroundings. In an
_____________ reaction, energy is transferred
to the __________.
3.
Breaking bonds is ___________ and absorbs or
takes in heat energy, while making bonds is
________ and ________ heat energy.
System, surroundings, heat
Look at the picture of an Endothermic change. Use it
to help you explain what is happening.
During Endothermic changes,
_________ energy is transferred
from the ________________to the
_____________________
System, surroundings, heat
Easy way to remember!!!
 EXothermic means heat energy is EXiting (leaving) the
reaction
 ENdothermic means heat energy is ENtering the reaction
Exothermic, System, Endothermic,
Products, Reactants, Transferred,
releases
Differences between Exothermic and Endothermic
reactions (circle the correct answer)
1. Absorbs energy from
the surroundings
Exothermic/ endothermic
2. Releases energy to the
surrounding
Exothermic/ endothermic
3. Reaction flask gets hot
Exothermic/ endothermic
4. Reaction flask becomes
cold
Exothermic/ endothermic
Exothermic and Endothermic Changes
State whether these reactions are exothermic or
endothermic (circle the correct answer)
1. Photosynthesis
Exothermic/ endothermic
2. Respiration
Exothermic/ endothermic
3. Combustion (burning of
fuels)
Exothermic/ endothermic
4. Neutralisation (acid +
base reacting)
Exothermic/ endothermic
Calculating temperature changes:
Complete the table below
Energy change = Final Temperature – Initial temperature
Final Temp (0 C)
Initial Temp (0 C)
Temperature
Change
50
20
50 -20 = 30
10
15
10 – 15 = -5
20
4
14
18
52
23
 If the final temperature is bigger than the initial
temperature, the reaction is exothermic
 If the final temperature is smaller than the initial
temperature, the reaction is endothermic
Fill in the blanks with exothermic or endothermic
the correct answer:
Final Temp (0 C)
Initial Temp (0 C)
50
20
10
15
20
4
14
18
52
23
EXOTHERMIC or
ENDOTHERMIC?
Summary:
Draw a diagram to show the difference between
exothermic and endothermic changes?