GCSE Topics 3 and 4 - Electrolysis and metal extraction

Question 1

Metals that are found native

Answer 1

silver, gold and platinum

Question 2

Metals that are extracted using reduction with carbon

Answer 2

zinc, iron, tin, lead, copper

Question 3

Least reactive metal

Answer 3

platinum

Question 4

Metals that are extracted using electrolysis

Answer 4

potassium, sodium, magnesium, calcium, aluminium

Question 5

Positive electrode

Answer 5

Anode

Question 6

Negative electrode

Answer 6

cathode

Question 7

Symbol equation for aluminium oxide electrolysis

Answer 7

Al₂O_{<span>3</span>} ⇒ 2 Al + 1.5 O₂

Question 8

Symbol equation for water electrolysis

Answer 8

2 H₂O _(l) ⇒ 2 H_{2 (g)} + O_{2 (g)}

Question 9

Symbol equation for brine electrolysis

Answer 9

2 NaCl _(aq) + 2 H₂O _(l) ⇒ 2 NaOH _(aq) + H_{2 (g)} + Cl_{2 (g)}

Question 10

Symbol equation for the reduction of iron oxide

Answer 10

2 Fe₂O_{3 (s)} + 3 C _(s) ⇒ 4 Fe _(s) + 3 CO_{2 (g)}

Question 11

Anode product of brine electrolysis, name

Answer 11

chlorine

Question 12

Cathode product of brine electrolysis, name

Answer 12

hydrogen

Question 13

Anode product of water electrolysis, name

Answer 13

oxygen

Question 14

Cathode product of water electrolysis, name

Answer 14

hydrogen

Question 15

Anode product of aqueous copper sulfate electrolysis, name

Answer 15

oxygen

Question 16

Cathode product of aqueous copper sulfate electrolysis, name

Answer 16

copper

Question 17

Anode product of hydrochloric acid electrolysis, name

Answer 17

chlorine

Question 18

Cathode product of hydrochloric acid electrolysis, name

Answer 18

hydrogen

Question 19

Anode product of aluminium oxide electrolysis, name

Answer 19

oxygen

Question 20

Cathode product of aluminium oxide electrolysis, name

Answer 20

aluminium

Question 21

Anode product of aqueous copper chloride electrolysis, name

Answer 21

chlorine

Question 22

Cathode product of aqueous copper chloride electrolysis, name

Answer 22

copper

Question 23

Cathode half equation for water electrolysis

Answer 23

2 H⁺ _(aq) + 2 e^- ⇒ H_{2 (g)}

Question 24

Anode half equation for water electrolysis

Answer 24

4 OH^- _(aq) ⇒ H₂O _(l) + O_{2 (g)} + 4 e^-

Question 25

Cathode half equation for aluminium oxide electrolysis

Answer 25

Al³⁺ + 3 e^- ⇒ Al

Question 26

Anode half equation for aluminium oxide electrolysis

Answer 26

2 O^2- ⇒ O₂ + 4 e^-

Question 27

Cathode half equation for aqueous copper sulfate electrolysis

Answer 27

Cu²⁺ _(aq) + 2 e^- ⇒ Cu _(s)

Question 28

Anode half equation for aqueous copper sulfate electrolysis

Answer 28

4 OH^- _(aq) ⇒ H₂O _(l) + O_{2 (g)} + 4 e^-

Question 29

Cathode half equation for aqueous copper chloride electrolysis

Answer 29

Cu²⁺ _(aq) + 2 e^- ⇒ Cu _(s)

Question 30

Anode half equation for aqueous copper chloride electrolysis

Answer 30

2 Cl^- _(aq) ⇒ Cl_{2 (g)}

Question 31

Test for hydrogen gas and result

Answer 31

Squeeky pop test Place a lit splint over a test tube. A positive result is a squeeky pop sound.

Question 32

Test for chlorine gas and result

Answer 32

Damp blue litmus paper Place a piece of damp blue litmus paper over a test tube. It will turn red and then be bleached white. The blue litmus turns red because chlorine reacts with water to produce hydrochloric acid.

Question 33

Test for oxygen gas and result

Answer 33

Glowing splint test Place a glowing splint over a test tube. It relights in the presence of oxygen.

Question 34

Electrolysis definition

Answer 34

Decomposition of an electrolyte compound into its elements using electricity from direct current.

Question 35

Cathode product of aqueous sodium sulfate electrolysis, name

Answer 35

hydrogen

Question 36

Anode product of aqueous sodium sulfate electrolysis, name

Answer 36

oxygen

Question 37

Cathode half equation for aqueous sodium sulfate electrolysis

Answer 37

2 H⁺ _(aq) + 2 e^- ⇒ H_{2 (g)}

Question 38

Anode half equation for aqueous sodium sulfate electrolysis

Answer 38

4 OH^- _(aq) ⇒ H₂O _(l) + O_{2 (g)} + 4 e^-

Question 39

Cathode product of molten lead bromide electrolysis, name

Answer 39

lead

Question 40

Anode product of molten lead bromide electrolysis, name

Answer 40

bromine

Question 41

Substance used to lower the temperature of aluminium oxide electrolysis

Answer 41

cryolite

Question 42

Conditions for electrolysis of ionic compounds

Answer 42

Molten or aqueous The ions are not free to move in the solid but are free to move in the molten compound or aqueous solution (NOT NOT delocalised electrons).

Question 43

Reduction, in terms of electrons

Answer 43

Gain of electrons

Question 44

Oxidation, in terms of electrons

Answer 44

Loss of electrons

Question 45

Reaction at the cathode

Answer 45

Reduction

Question 46

Reaction at the anode

Answer 46

Oxidation

Question 47

Explanation for loss of mass of the anode in aluminium oxide electrolysis

Answer 47

* The anode is made of graphite (carbon) * Oxygen gas is produced at the anode * Oxygen reacts with the electrode in a combustion reaction * Carbon dioxide gas is produced * Carbon dioxide escapes

Question 48

Explanation for gain of mass of the cathode in aqueous copper sulfate electrolysis

Answer 48

* Aqueous copper sulfate contains Cu²⁺ ions * The copper ions are reduced * A layer of copper atoms are formed on the cathode * The half equation for the reaction is * Cu²⁺ _(aq) + 2 e^- ⇒ Cu _(s)

Question 49

Phytomining or Phytoextraction

Answer 49

* Extraction of a metal using plants * Plants grow on soil with a concentration of metal too low to make a profit from mining * Plants concentrate the metal in their sap * The plant is burned to leave ash, the energy produced from this may be used to generate electricity * The ash is dissolved in water, heated then filtered * Electrolysis is used. The metal is produced at the cathode.

Question 50

Explanation of metal reactivity

Answer 50

* Metals are oxidised. * Metal atoms lose electrons to become cations. * The more reactive a metal is, the more easily oxidised it is. * Metals that are resistant to oxidation are less reactive

Question 51

The four ions present in aqueous sodium chloride (brine)

Answer 51

Na⁺ , Cl^- , H⁺ , OH^-

Question 52

The three ions present in hydrochloric acid

Answer 52

H⁺ , Cl^- OH^-

Question 53

The four ions present in aqueous copper chloride

Answer 53

H⁺ , Cu²⁺ , Cl^- , OH^-

Question 54

The four ions present in aqueous copper sulfate

Answer 54

H⁺ , OH^- , SO₄^2-

Question 55

Copper sulfate solution

Answer 55

Question 56

Diagram of aluminium oxide electrolysis

Answer 56

Question 57

Diagram of aqueous sodium chloride electrolysis

Answer 57