Energy Transfer in Reactions Flashcards Preview

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Flashcards in Energy Transfer in Reactions Deck (14)
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1
Q

What is an exothermic reaction?

A

An exothermic reaction is one which gives out energy to the surroundings, usually in the form of heat and usually shown by a raise in temp

2
Q

Name 3 exothermic reactions

A

1) Burning fuels: Combustion
2) Neutralisation reactions
3) Oxidation reactions

3
Q

What are the recants in neutralisation reaction?

A

Acid and an alkali

4
Q

Give an example of an oxidation reaction

A

Adding sodium to water produces heat. The sodium emits heats and moves about on the surface of the water as it is oxidised

5
Q

Name 2 everyday uses of exothermic reaction and explain them

A

1) Hand warmers use exothermic oxidation of iron in air (with a salt solution catalyst) to generate heat.
2) Self-heating cans of drinks rely on exothermic reactions between chemicals and their bases

6
Q

What is an endothermic reaction?

A

An endothermic reaction is one which takes in energy from the surroundings, usually in the form of heat and usually shown by a fall in temp

7
Q

What is a good example of an endothermic reaction?

A

Thermal decompositions

8
Q

Heat must be supplied to make calcium carbonate decompose to make [ ].
What’s the symbol equation?

A

quicklime

CaCO₃ -> CaO + CO₂

9
Q

Name an everyday use of endothermic reactions

A

Sports injury packs - they take in heat and the pack becomes very cold

10
Q

Describe endo/exo - ness in reversible reactions

A

If the reaction is endothermic in 1 direction then it will be exothermic in the other direction. The energy absorbed by the endothermic reaction is equal to the energy release during the exothermic reaction

11
Q

What is a good example of a reversible reaction?

A

Thermal decomposition of hydrated copper sulphate

12
Q

What is he word equation for the thermal decomposition of hydrated copper sulphate?

A

Hydrated copper sulphate (reversible sign) anhydrous copper sulphate + water

—-> Endothermic

13
Q

Describe the endothermic reaction of the thermal decomposition of hydrated copper sulphate

A

If you heat blue hydrated copper (II) sulphate crystals it drives the water off and leaves white anhydrous copper (II) sulphate powder. -> Endothermic

14
Q

Describe the exothermic reaction of the thermal decomposition of hydrated copper sulphate

A

If you then add a couple of drops of water to the white powder (from the endothermic reaction) you get blue crystals again