C7 - Energy Changes

Question 1

Exothermic Reaction

Answer 1

• Releases energy to the surrounding, increase temperature

- E.g. Combustion (burning fuels) and many Oxidation Reactions

Question 2

Endothermic Reaction

Answer 2

• Takes in energy, decreases temperature

- Melting Ice Cubes

Question 3

Measuring Energy Transfer

Answer 3

1. Put 25cm^3 (Volume) and 0.25mol/dm^3 (Concentration) of HCl and NaOH into separate beakers
2. Put them into a water bath at 25 degrees, until both reach the same temperature
3. Add HCl and NaOH into a polystyrene cup with a lid
4. Record the temperature of the mixture every 30 seconds and record the highest temperature
5. Repeat steps with a higher concentration of HCl

Question 4

Bond Making/Breaking

Answer 4

• Energy released from bonds (form) is greater than energy taken into bonds (break)
• Product to Reactant, Exothermic

Question 5

Bond Breaking

Answer 5

• Energy taken in from bonds (break) is greater than energy released from bonds (form)
• Reactant to Product, Endothermic

Question 6

Internal Energy Store

Answer 6

• Energy used in an Endo/Exothermic reaction

Question 7

Thermal Decomposition

Answer 7

• When compounds are broken down when heated forming 2 products from one reaction

Question 8

Neutralisation

Answer 8

• A reaction where an acid reacts with an Alkali to form a neutral solution of salt and water

Question 9

Uses of Exothermic

Answer 9

• Handwarmers

- Self heating cans

Question 10

Uses of Endothermic

Answer 10

• Ice packs for bruising

Question 11

Activation Energy

Answer 11

• The highest point of the graph before it goes down

Question 12

Endothermic graph trend

Answer 12

• Reactant have less energy than Products

Question 13

Exothermic graph trend

Answer 13

• Reactants have more energy than products

Question 14

Catalysts

Answer 14

• Speed up chemical reactions, give quicker alternative pathway for reactants to collide
• Lower activation energy, less energy used