C4

Question 1

What happens when metals react with oxygen?

Answer 1

Metal oxide

Question 2

Oxidation is loss of … and gain of …

Answer 2

Loss of electrons and gain of oxygen

Question 3

Reduction is gain of … and loss of …

Answer 3

Gain of electrons and loss of oxygen

Question 4

What’s the order of the reactivity series?

Answer 4

potassium, sodium, lithium, calcium, magnesium, carbon, zinc, iron, hydrogen, copper, silver and gold

Question 5

What is displacement of metals?

Answer 5

A more reactive metal can displace a less reactive metal from a compound.

Question 6

Where is gold found and what’s it called?

Answer 6

In the ground, as an ore.

Question 7

To get metals which are more reactive than carbon on their own, what do you do?

Answer 7

Electrolysis

Question 8

To get metals which are less reactive than carbon on their own, what do you do?

Answer 8

Reduction with carbon

Question 9

Equation for neutralisation

Answer 9

Acid + alkali = salt + water

Question 10

Acids form what ions in water?

Answer 10

H+

Question 11

Alkalis form what ions in water?

Answer 11

OH-

Question 12

Equation for neutralisation with symbols

Answer 12

H+ + OH- –> H2O

Question 13

Acid + metal =

Answer 13

salt + hydrogen

Question 14

Metal + water =

Answer 14

metal hydroxide + hydrogen

Question 15

Metal oxide + acid =

Answer 15

salt (metal sulfate etc) + water

Question 16

Metal carbonate + acid =

Answer 16

salt, carbon dioxide and water

Question 17

Making a salt practical

Answer 17

• Using metals, metal oxides, hydroxides or carbonates.- Heat acid to speed up reaction - The solid is added to the acid in excess - Solid is filtered- Put solution over Bunsen burner and gently heat - Leave overnight to crystallise.

Question 18

pH scale

Answer 18

Measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14

Question 19

Titration practical

Answer 19

• Measure 25cm3 of sodium hydroxide (known) using a pipette to a conical flask.- Add an indicator to conical flask.- Place on a white tile to see colour change more clearly.- Add acid from burette and swirl

Question 20

Equation for titration

Answer 20

Sulfuric acid + sodium hydroxide = sodium sulfate + water

Question 21

Examples of strong acids

Answer 21

hydrochloric, nitric and sulfuric acids.

Question 22

What does a strong acid do?

Answer 22

Completely ionise in an aqueous solution

Question 23

Examples of weak acids

Answer 23

ethanoic, citric and carbonic acids.

Question 24

What does a weak acid do?

Answer 24

Partially ionise in aqueous solutions

Question 25

As the pH decreases by one unit, what happens?

Answer 25

The hydrogen ion concentration of the solution increases by a factor of 10

Question 26

What's an electrolyte?

Answer 26

When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity.

Question 27

Positively charged ions go where?

Answer 27

Move to the negative electrode, the cathode

Question 28

Negative charged ions go where?

Answer 28

The positive electrode, the anode

Question 29

Half equation for anode for chlorine

Answer 29

2Cl- → Cl2 + 2e-

Question 30

Half equation for cathode for Copper(II) chloride (CuCl2)

Answer 30

Cu2+ + 2e-→ Cu

Question 31

What does electrolysis mean?

Answer 31

Splitting up with electricty

Question 32

Why can molten ionic compounds be split up with electrolysis?

Answer 32

Their ions can move freely

Question 33

Why is electrolysis used?

Answer 33

To split up metals which are more reactive than carbon

Question 34

Why is a mixture used as the electrolyte?

Answer 34

Because a mixture of positive and negative ions are needed

Question 35

Disadvantage of electrolysis

Answer 35

Needs lots of energy so very expensive

Question 36

What's a cryolite?

Answer 36

Cryolite acts as a solvent and allows the electrolysis to take place at a lower temperature.

Question 37

Why does using carbon at the anode mean the electrode needs to be completely replaced?

Answer 37

Carbon reacts with 02 so produces C02 which means the carbon is lost

Question 38

Give an example of electrolysis

Answer 38

Aluminium oxide --> aluminium + oxygen

Question 39

What happens if the metal is more reactive than hydrogen at the cathode?

Answer 39

At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen

Question 40

What happens if there's a halogen present at the anode?

Answer 40

At the positive electrode (anode), oxygen is produced unless the solution contains halide ions when the halogen is produced.

Question 41

Practical 3 - investigate what happens when aqueous solutions are electrolysed using inert electrodes.

Answer 41

1. Add the aqueous solution to the beaker 2. Add two graphite rods as the electrodes and connect this to a power pack or battery 3. Turn on the power pack or battery and allow electrolysis to take place 4. Record the results in a suitable table and repeat for another solution, checking the electrodes in between runs to see if any metal has been deposited 5. The gases produced can be collected in the test tubes to be tested later

Question 42

Is the reaction at the cathode a reduction or oxidation?

Answer 42

During electrolysis, at the cathode (negative electrode), positively charged ions (metals) gain electrons and so the reactions are reductions

Question 43

Is the reaction at the anode a reduction or oxidation?

Answer 43

At the anode (positive electrode), negatively charged ions lose electrons and so the reactions are oxidations