Topic 4: Chemical Changes

Question 1

What ions do acids form when they dissolve in water (an aqueous solution)?

Answer 1

Hydrogen ions (H+)

Question 2

What ions do alkalis form when they dissolve in water (an aqueous solution)?

Answer 2

Hydroxide ions (OH-)

Question 3

What does a pH scale measure?

Answer 3

How acidic or Alkaline a substance is.

Question 4

What does an oxidation reaction involve?

Answer 4

Gaining oxygen and losing electrons

Question 5

What does a reduction reaction involve?

Answer 5

Losing oxygen and gaining electrons

Question 6

When a substance is oxidised, it always…

Answer 6

…Loses electrons

Question 7

When a substance is reduced, it always…

Answer 7

…Gains electrons

Question 8

What is OILRIG?

Answer 8

Oxidation
Is
Loss
Reduction
Is
Gain

Question 9

What happens in a displacement reaction?

Answer 9

A more reactive metal (one that forms positive ions more easing) removes a less reactive metal from a compound.

Question 10

A metal can only displays above metal from a compound if it is located _______ it in the reactivity series

Answer 10

Above.

Question 11

What can more reactive substances do in a displacement reaction?

Answer 11

They can replace less reactive substances from compounds.

Question 12

Complete this displacement reaction:

Sodium Bromide + Chlorine -> ? + ?

Answer 12

Sodium Bromide + Chlorine -> Sodium Chloride + Bromine

Bromide ions are oxidised (electrons are lost)
2Br- ->Br2 + 2e-

Chlorine is reduced (electrons are gained)
Cl2 +2e- -> 2Cl-

Sodium remains unchanged as it is a spectator ion in this reaction.

Question 13

What is a spectator ion?

Answer 13

Ions that remain unchanged in the reaction.

Question 14

When reacting with other substances, metal atoms always form….

Answer 14

Positive ions

Question 15

What is the reactivity of a metal linked to?

Answer 15

How easy it is for a metal to form it’s positive ion.

Question 16

How can metals be arranged?

Answer 16

In order of reactivity.

Question 17

What are native metals?

Answer 17

Metals that are found in the Earth’s crust as pure metals that are highly unreactive.

Question 18

Name 2 examples of native metals.

Answer 18

Gold and Platinum, which are both highly UNREACTIVE.

Question 19

What charge do ions normally get from metal atoms?

Answer 19

A positive charge.

Question 20

What charge ions normally form from metal atoms?

Answer 20

Positive ions

Question 21

What 3 metals all react quickly with cold water to produce metal hydroxide + Hydrogen gas?

Answer 21

Potassium, sodium and lithium
(in ascending order)

Question 21

What colour flame is produced when potassium reacts with water?

Answer 21

A lilac flame.

Question 22

What do metals react with dilute acid to give?

Answer 22

a salt and hydrogen gas

Question 23

Name 5 examples of metals that react with dilute acids but not with cold water?

Answer 23

Magnesium
Aluminium
Zinc
Iron
Lead

Question 24

Name 4 metals that are not reactive enough to react with dilute acids. (think jewellery)

Answer 24

Copper Silver Gold Platinum

Question 25

Metal + Water =

Answer 25

Metal + Water -> Metal Hydroxide + Hydrogen

Question 26

Metal + Dilute Acid =

Answer 26

Metal + Dilute Acid -> A Salt + Hydrogen

Question 27

Name 2 reasons why carbon is used to extract many metals.

Answer 27

Cheap Abundant

Question 28

In what conditions does reducing a metal with carbon will extract the metal?

Answer 28

the metal has to be lower in the reactivity series than carbon.

Question 29

How is carbon used to extract metals?

Answer 29

in reduction, metal uses oxygen to form a pure metal, which is done by heating the metal oxide with the presence of carbon, usually coal.

Question 30

What is always formed when acids react with metals?

Answer 30

Hydrogen and a salt

Question 31

Magnesium + Hydrochloric Acid =

Answer 31

Magnesium + Hydrochloric Acid -> magnesium chloride + hydrogen

Question 32

Zinc + Sulfuric Acid =

Answer 32

Zinc + Sulfuric Acid -> Zinc Sulfate + Hydrogen

Question 33

What 2 reactions do redox reactions involve?

Answer 33

Oxidation and Reduction.

Question 34

Are spectator ions included in the ionic equation?

Answer 34

No.

Question 35

how are acids neutralised?

Answer 35

by reacting them with bases (an alkali is a based that dissolves by water)

Question 36

what do acid + metal carbonate make?

Answer 36

a salt + water + CO2

Question 37

hydrochloric acid + calcium carbonate ->

Answer 37

-> calcium chloride + water + CO2

Question 38

Acid + metal oxide ->

Answer 38

-> a salt + water

Question 39

acid + hydroxide ->

Answer 39

-> a salt + water

Question 40

hydrochloric acid + magnesium oxide ->

Answer 40

-> magnesium chloride + water

Question 41

hydrochloric acid + sodium hydroxide ->

Answer 41

-> sodium chloride + water

Question 42

what are soluble salts?

Answer 42

salts that dissolve in water

Question 43

how do we produce soluble salts?

Answer 43

by reacting an acid and a solid insoluble substance (such as a pure metal, metal carbonates etc.)

Question 44

How are blue copper sulfate crystals formed?

Answer 44

By adding black copper oxide to sulfuric acid

Question 45

DID NOT DO RP