C4

Question 1

metal carbonate + acid –> ______ +__________ + ______

Answer 1

salt + water + CO2

Question 2

metal + acid –> _____+____

Answer 2

salt + hydrogen

Question 3

acid + metal oxide —> ___+ ___

Answer 3

salt + water

Question 4

what does oxidation mean?

Answer 4

the gain of oxygen
- the substance that gains oxygen has been oxidised

Question 5

what does reduction mean?

Answer 5

the loss of oxygen
- the substance that lost oxygen has been reduced

Question 6

PRACTICAL: making pure dry copper sulphate crystals

Answer 6

1. measure 25cm^3 of sulfuric acid
2. heat gently on bunsen burner, tripod, gauze and heat proof mat
3. remove solution from bunsen burner and add copper oxide to acid with spatula and stir
4. add excess copper oxide until no more will dissolve
5. filter the mixture with filter paper, filter funnel and conical flask
6. pour filtered solution into evaporating basin
7. leave to dry in cool pace for 24 hours
8. remove crystals from solution with a spatula
9. gently pat crystals with filter paper
10. you now have pure dry crystals of copper sulphate

Question 7

what is oxidation in terms of electrons?

Answer 7

the loss of electrons

Question 8

what is reduction in terms of electrons?

Answer 8

the gain of electrons

Question 9

what is an ore?

Answer 9

a rock that contains a metal compound

Question 10

what are bases?

Answer 10

chemicals that neutralise acids

Question 11

what do bases produce?

Answer 11

a salt and water

Question 12

what do acids produce in aqueous solutions?

Answer 12

hydrogen ions (H+ ion)

Question 13

what are bases that are soluble in water also called?

Answer 13

alkalis

Question 14

what do alkalis produce in aqueous solutions?

Answer 14

hydroxide ions (OH-)

Question 15

which metals are extracted by heating with carbon?

Answer 15

metals less reactive than carbon

Question 16

which metals are extracted by electrolysis?

Answer 16

metals more reactive than carbon

Question 17

what 5 are signs a chemical reaction has taken place?

Answer 17

1. fizzing
2. colour change
3. temperature change
4. formation of a precipitate
5. change in smell

Question 18

what happens in displacement reaction?

Answer 18

a more reactive element will displace a less reactive element and form a compound

Question 19

what ion do all salts have?

Answer 19

a positive ion

Question 20

what is an acid?

Answer 20

a substance that releases H+ ions into solutions

Question 21

what is an alkali?

Answer 21

a substance that release OH- ions into solutions

Question 22

practical: why do you heat the acid gently first when making a salt?

Answer 22

to speed up the reaction

Question 23

practical: why do you stir the solution after adding each spatula of metal oxide?

Answer 23

to make sure it’s fully neutralised

Question 24

practical: what observation would be made when a metal oxide can no longer react with an acid?

Answer 24

the insoluble metal oxide remained in the beaker

Question 25

what do strong acids do in solutions?

Answer 25

fully ionise

Question 26

what are 3 examples of strong acids?

Answer 26

hydrochloric acid, sulfuric acid, nitric acid

Question 27

what do weak acids do in solutions?

Answer 27

partially ionise in solutuion

Question 28

what are some examples of weak acids?

Answer 28

methanoic acid and ethanoic acid (vinegar)

Question 29

concentrated acids have...

Answer 29

have a larger number of acid particles per volume of water

Question 30

Dilute acids (less concentrated) have...

Answer 30

a smaller number of acid particles per volume of water

Question 31

what does a lower pH means in terms of hydrogen ion concentration?

Answer 31

lower pH = lower hydrogen ion concentration

Question 32

what is electrolysis?

Answer 32

splitting up with electricity

Question 33

what does electrolysis do?

Answer 33

separates elements in insoluble ionic compounds

Question 34

electrolysis: what are electrodes

Answer 34

solid conductors that are generally made of metal or carbon

Question 35

electrolysis: where are the electrodes placed and what are they connected to?

Answer 35

- place in a liquid (electrolyte) - connected to a wire

Question 36

what is an electrolyte?

Answer 36

a liquid or solution that contains an ionic compound that is molten or dissolved (is free to move)

Question 37

what are the positive and negative electrodes called?

Answer 37

positive: anode negative: cathode

Question 38

what are cations and anions?

Answer 38

cations = positively charged ions (metals) anions = negatively charged ions (non- metals)

Question 39

electrolysis: why is the electrode connected to a wire?

Answer 39

so that the electrons can flow between them

Question 40

electrolysis: why do you need to add a power supply (e.g a battery)

Answer 40

- to drive the flow of electrons battery is used to pass an electric current through the electrolyte

Question 41

why do solid ionic compounds not conduct electricity?

Answer 41

because their ions are held in place by strong electrostatic forces of attraction so the ions can't move

Question 42

what happens when an ionic compound in melted or dissolved in water?

Answer 42

the forces of attractions are broken and the ions are free to move

Question 43

electrolysis: what is the negative cathode attached to?

Answer 43

the negative terminal of the power pack

Question 44

electrolysis: what is the positive anode attached to?

Answer 44

the positive terminal of the powerpack

Question 45

why is electrolysis expensive?

Answer 45

melting compounds with high melting and boiling points requires a great deal of energy. - a lot of energy is needed to produce an electric current

Question 46

what do water molecules form when they are ionised?

Answer 46

hydrogen and hydroxide ions

Question 47

electrolysis: when is hydrogen produced at the cathode?

Answer 47

if the metal is more reactive than hydrogen

Question 48

what does aqueous mean?

Answer 48

dissolves in water

Question 49

electrolysis: what happens if the aqueous solution contains halide ions?

Answer 49

the halogen will be produced at the anode

Question 50

electrolysis: how can we tell if a gas being produced is a chlorine gas?

Answer 50

if we hold a piece of damp blue litmus paper near the anode and it becomes bleached

Question 51

why is cyrolite used to dissole (the alluminium oxide)

Answer 51

because it has melting point of over 2000 degrees so it reduces the cost of heating

Question 52

what must the electrodes be made of?

Answer 52

unreactive/ inert metals/elements e,g graphite and platinum

Question 53

why do electrodes have to be replaced every few months?

Answer 53

because it burns away

Question 54

what is an acid?

Answer 54

a substance that produces H+ ions into solutions

Question 55

what is an acid?

Answer 55

a substance that produces H+ ions into solutions

Question 56

what uis

Question 58

Dont have the steps for electrolysis required practical