The document discusses endothermic reactions. It states that endothermic reactions absorb thermal energy, causing a decrease in temperature. Examples of endothermic reactions given include thermal decomposition of calcium carbonate in a blast furnace, photosynthesis, some types of electrolysis, and the melting of sherbet.

1. Endothermic reactions
Endothermic reactions absorb thermal energy, and so
cause a decrease in temperature.
What are some examples?
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2. Endothermic reactions
Endothermic reactions absorb thermal energy, and so
cause a decrease in temperature.
What are some examples?
 thermal
decomposition, e.g.
calcium carbonate in
a blast furnace
2 of 35 © Boardworks Ltd 2007

3. Endothermic reactions
Endothermic reactions absorb thermal energy, and so
cause a decrease in temperature.
What are some examples?
 thermal
decomposition, e.g.
calcium carbonate in
a blast furnace
 photosynthesis
3 of 35 © Boardworks Ltd 2007

4. Endothermic reactions
Endothermic reactions absorb thermal energy, and so
cause a decrease in temperature.
What are some examples?
 thermal
decomposition, e.g.
calcium carbonate in
a blast furnace
 photosynthesis
 some types of
electrolysis
4 of 35 © Boardworks Ltd 2007

5. Endothermic reactions
Endothermic reactions absorb thermal energy, and so
cause a decrease in temperature.
What are some examples?
 thermal
decomposition, e.g.
calcium carbonate in
a blast furnace
 photosynthesis
 some types of
electrolysis
 sherbet!
5 of 35 © Boardworks Ltd 2007

6. Endothermic reaction: energy transfer
What happens to energy in the reaction between
ammonium nitrate and water?
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7. Endothermic reaction: energy transfer
What happens to energy in the reaction between
ammonium nitrate and water?
 During the reaction, thermal energy
from the reaction mixture is converted
to chemical energy in the products.
7 of 35 © Boardworks Ltd 2007

8. Endothermic reaction: energy transfer
What happens to energy in the reaction between
ammonium nitrate and water?
 During the reaction, thermal energy
from the reaction mixture is converted
to chemical energy in the products.
 This causes the temperature of the
reaction mixture to fall.
8 of 35 © Boardworks Ltd 2007

9. Endothermic reaction: energy transfer
What happens to energy in the reaction between
ammonium nitrate and water?
 During the reaction, thermal energy
from the reaction mixture is converted
to chemical energy in the products.
 This causes the temperature of the
reaction mixture to fall.
 Thermal energy from the
surroundings is transferred to the
reaction mixture, and the temperature
eventually returns to normal.
9 of 35 © Boardworks Ltd 2007