Changes on heating chemicals

Question 1

What is a physical change?

Answer 1

A physical change is when a substance changes without forming new substances, like changing state or colour. This change is usually reversible

Question 2

What is a chemical change?

Answer 2

A chemical change is when a substance changes completely, involving the creation of new substances. This change is usually irreversible.

Question 3

What does wax look like before heating, during heating, and after heating?

Answer 3

White solid, colourless liquid, white solid

Question 4

What does ice look like before heating, during heating, and after heating?

Answer 4

Colourless solid, colourless liquid, colourless liquid

Question 5

What does sodium chloride look like before heating, during heating, and after heating?

Answer 5

White solid, white solid, white solid

Question 6

What does Ammonium chloride look like before heating, during heating, and after heating?

Answer 6

White solid, white gas, white solid

Question 7

What does zinc oxide look like before heating, during heating, and after heating?

Answer 7

White solid, yellow solid, white solid

Question 8

What colour is zinc oxide when you heat it?

Answer 8

Yellow

Question 9

How does wax change when you heat it?

Answer 9

It melts to become a colourless liquid

Question 10

What is the transition from a liquid to a solid?

Answer 10

Freezing

Question 11

What is the transition from a liquid to a gas?

Answer 11

Evaporating

Question 12

What is the transition from a gas to a liquid?

Answer 12

condensation

Question 13

What is the transition from a solid to a gas?

Answer 13

sublimation

Question 14

How can you tell if something has chemically changed?

Answer 14

chemical changes can change colour, smell, releases light or gases, give off or take in heat

Question 15

What is thermal decomposition?

Answer 15

the breaking down of a substance because of heat (in decomposition there is always more products than reactants)

Question 16

What is synthesis?

Answer 16

when two substances are combined to form a new one (in synthesis there is always more reactants that products)

Question 17

What are reactants?

Answer 17

the substances that you start with

Question 18

What are products?

Answer 18

the substances that are made (produced) as a result of chemical change

Question 19

What happens to the mass of a substance when it decomposes?

Answer 19

it loses mass

Question 20

What happens to the mass of a substance when it synthesises?

Answer 20

it gains mass

Question 21

What is the colour of Copper (ll) carbonate before heating?

Answer 21

green

Question 22

What is the colour of the new solid created after Copper (ll) carbonate is heated?

Answer 22

black

Question 23

How do we know if a substance has carbon dioxide in it?

Answer 23

it turns lime water milky white

Question 24

What happened to the mass of copper (ll) carbonate when it was heated?

Answer 24

it decreased because carbon dioxide was released and it undergoes thermal decomposition

Question 25

Why is carbon dioxide released from copper (ll) carbonate?

Answer 25

because it's being heated

Question 26

What is the word equation for the heating of copper (ll) carbonate?

Answer 26

copper (ll) carbonate→copper (ll) oxide + carbon dioxide

Question 27

Does copper (ll) carbonate go through a physical or chemical change when heated?

Answer 27

chemical change because it undergoes thermal decomposition

Question 28

What colour is copper (ll) sulphate before heating?

Answer 28

blue

Question 29

what colour is copper (ll) sulphate after heating?

Answer 29

white

Question 30

What happens as the copper (ll) sulphate crystals are being heated?

Answer 30

the water evaporates, the colour changed, and there was condensation

Question 31

Is the heating of copper (ll) sulphate a physical or chemical change?

Answer 31

chemical change because it undergoes thermal decomposition (its mass decreases)

Question 32

Is the heating of copper (ll) sulphate reversible or irreversible?

Answer 32

reversible, if you put water on a sample of anhydrous copper (ll) sulphate, it will turn from white to blue again

Question 33

What is lost by the copper (ll) sulphate crystals as they are being heated?

Answer 33

water

Question 34

what are crystals that contain water called?

Answer 34

hydrated

Question 35

What is the solid called after the water has been lost by the crystals?

Answer 35

anhydrous

Question 36

What is the word equation for the heating of copper (ll) sulphate?

Answer 36

hydrated copper (ll) sulphate ⇌ anhydrous copper (ll) sulphate + water

Question 37

What does "⇌" mean?

Answer 37

that the process is reversible

Question 38

What suggests that water is given out when copper (ll) sulphate is heated?

Answer 38

a colourless gas is given off, which condenses to a colourless liquid on the cooler parts of the tube

Question 39

What is a reaction with oxygen called?

Answer 39

oxidation