Energy Changes & States of Matter

Question 1

What is exothermic reaction?

Answer 1

Reaction that releases energy to surroundings, temperature increases

Question 2

What is endothermic reaction?

Answer 2

Reaction that takes in energy from surroundings, temperature decreases

Question 3

Is melting endothermic or exothermic?

Answer 3

Endothermic (energy needed to break bonds)

Question 4

Is condensing endothermic or exothermic?

Answer 4

Exothermic (energy released when bonds form)

Question 5

Is evaporation endothermic or exothermic?

Answer 5

Endothermic (energy needed to break bonds)

Question 6

Is boiling endothermic or exothermic?

Answer 6

Endothermic (energy needed to break bonds)

Question 7

Is freezing endothermic or exothermic?

Answer 7

Exothermic (energy released when bonds form)

Question 8

Is sublimation endothermic or exothermic?

Answer 8

Endothermic (energy needed to break bonds)

Question 9

What happens to temperature in an exothermic reaction?

Answer 9

Goes up

Question 10

What happens to temperature in an endothermic reaction?

Answer 10

Goes down

Question 11

Name two examples of exothermic reactions

Answer 11

Combustion, neutralisation, respiration

Question 12

Name two examples of endothermic reactions

Answer 12

Thermal decomposition, photosynthesis

Question 13

The bonds between atoms of reactants need to be broken first - is this endothermic or exothermic?

Answer 13

Endothermic

Question 14

New bonds are made between atoms of products - is this endothermic or exothermic?

Answer 14

Exothermic

Question 15

Reaction A: starts 20°C, ends 31°C - endothermic or exothermic?

Answer 15

Exothermic (temperature increased by 11°C)

Question 16

Reaction B: starts 22°C, ends 18°C - endothermic or exothermic?

Answer 16

Endothermic (temperature decreased by 4°C)

Question 17

Reaction C: starts 21°C, ends 25°C - endothermic or exothermic?

Answer 17

Exothermic (temperature increased by 4°C)

Question 18

Which reaction (A: 20→31°C, B: 22→18°C, C: 21→25°C) has largest energy change?

Answer 18

Reaction A (11°C change)

Question 19

How are particles arranged in a solid?

Answer 19

Close together in regular pattern, vibrate in fixed positions

Question 20

How are particles arranged in a liquid?

Answer 20

Close together but irregular arrangement, can move around each other

Question 21

How are particles arranged in a gas?

Answer 21

Far apart, move randomly in all directions at high speed

Question 22

What is a physical change?

Answer 22

A change where no new substances are formed and the change is reversible

Question 23

What is a chemical change?

Answer 23

A change where new substances are formed and the change is usually irreversible

Question 24

Give an example of a physical change

Answer 24

Melting ice, dissolving sugar, boiling water

Question 25

Give an example of a chemical change

Answer 25

Burning wood, rusting iron, cooking an egg