C4

Question 1

Metal + oxygen is what and what reaction takes place?

Answer 1

Metal oxide, oxidation reaction

Question 2

What happens in an oxidation reaction?

Answer 2

Oxygen is gained and electrons are lost.

Question 3

What happens in a reduction reaction?

Answer 3

Oxygen is lost and electrons are gained.

Question 4

G1 metal + water is what

Answer 4

Metal hydroxide (alkali) + hydrogen

Question 5

What metals do not react with water at room temperature?

Answer 5

Magnesium, zinc, iron, copper

Question 6

What metals react rapidly and quite rapidly with water at room temperature?

Answer 6

Potassium, sodium, lithium and (calcium reacts quite rapidly).

Question 7

What does the reactivity of a metal depend on?

Answer 7

Its ability to lose electrons and from a positive ion.

Question 8

Half equation for oxidation for magnesium

Answer 8

Mg -> Mg2+ + 2e-

Question 9

Half equation for reduction for sulfur

Answer 9

S + 2e- -> S2-

Question 10

What ions do acids produce in aqueous solutions?

Answer 10

Hydrogen ions (H+)

Question 11

Acid + base is what and what type of reaction is it?

Answer 11

Salt + water, neutralisation reaction

Question 12

What are bases usually?

Answer 12

Metal oxides or metal hydroxides

Question 13

Define alkali

Answer 13

A base that is soluble in water.

Question 14

What ions do alkalis produce in aqueous solutions?

Answer 14

Hydroxide ions (OH-)

Question 15

H+ + OH- is what

Answer 15

H2O - water

Question 16

Metal + water is what and what reaction is it?

Answer 16

Salt + hydrogen, displacement reaction (metal has displaced the hydrogen)

Question 17

In a metal + acid reaction, what is oxidised and what is reduced?

Answer 17

Metals are oxidised and acid is reduced

Question 18

Define base

Answer 18

Chemicals which can neutralise acids and produce a salt and water.

Question 19

Acid + metal carbonate is what?

Answer 19

Salt + water + carbon dioxide

Question 20

How to make soluble salts (practical)?

Answer 20

1. Warm the dilute acid using a Bunsen burner, then turn it off.
2. Add the insoluble base to the acid a bit at a time, until no more reacts (the base is in excess).
   The acid will be neutralised when the excess solid will just sink to the bottom of the flask.
3. Filter out the excess solid to get the salt solution.
4. To get pure, solid crystals of the salt, leave the solution for 24 hours in a cool place.
   Crystals should form, which can be filtered out the solution and then dried using a paper towel - crystallisation.

Question 21

What happens to acid molecules in solution?

Answer 21

Acid molecules ionise (split) and release H+.

Question 22

How do strong acids ionise in aqeous solutions?

Answer 22

Fully ionise is aqueous solutions.

Question 23

3 strong acids

Answer 23

Hydrochloric / sulfuric / nitric acid

Question 24

How do weak acids ionise in aqeous solutions?

Answer 24

Partially ionise in aqueous solutions (reversible reaction).

Question 25

3 weak acids

Answer 25

Carbonic / ethanoic / citric acid

Question 26

Why do strong acids have a lower pH than weak acids?

Answer 26

Strong acids fully ionise creating a greater concentration of hydrogen ions than weak acids.

Question 27

How many times greater is the concentration of H+ in pH 1 than 2?

Answer 27

10x greater (one order of magnitude)

Question 28

Define the concentration of an acid

Answer 28

The amount of acid molecules in a given volume of solution. A dilute acid will have fewer acid molecules in a given volume than a concentrated acid even if the strength is the same.

Question 29

How to make an ionic compound conduct electricity?

Answer 29

Melt it or dissolve in water - the forces of attraction are broken and ions are free to move.

Question 30

What is the negative and positive electrode called and what are they covered with?

Answer 30

Cathode - colvered with electrons, anode - lack of electrons

Question 31

Which electrode are the positive ions attracted to what reaction is it?

Answer 31

The negative electrode - cathode, reduction reaction.

Question 32

Which electrode are the negative ions attracted to what reaction is it?

Answer 32

The positive electrode - anode, oxidation reaction.

Question 33

Metals that are more reactive than carbon are extracted using what?

Answer 33

Electrolysis

Question 34

Metals that are less reactive than carbon are extracted using what?

Answer 34

Carbon

Question 35

How is electrolysis of aluminium oxide done?

Answer 35

1. Aluminium oxide is mixed with cryolite with lowers the melting point - reduces the amount of energy needed and saves money. 2. The cathode attracts the positive aluminium ions and the negative oxide ions attracts to the anode.

Question 36

Why must the anode be replaced regularly?

Answer 36

The oxygen molecules produced at the anode reach with the graphite (carbon), forming carbon dioxide gas. C + O2 -> CO2

Question 37

Why is electrolysis expensive?

Answer 37

Melting the compounds requires a great deal of energy and a lot of energy is required to produce the electric current.

Question 38

In the electrolysis of aqueous solutions, what is produced at the cathode if the metal is more reactive then hydrogen? What is the half equation?

Answer 38

Hydrogen, 2H+ + 2e- -> H2

Question 39

In the electrolysis of aqueous solutions, what is produced at the cathode if the metal is less reactive then hydrogen? What is the half equation?

Answer 39

Pure metal, Cu2+ + 2e- -> Cu

Question 40

In the electrolysis of aqueous solutions, what is produced at the anode if a halide ion is present? What is the half equation?

Answer 40

Halogen gas, Cl- -> Cl2 + 2e-

Question 41

In the electrolysis of aqueous solutions, what is produced at the anode if a halide ion is not present? What is the half equation?

Answer 41

Oxygen, 4OH- - 4E- -> 2H2O + O2

Question 42

Test for chlorine gas

Answer 42

Bleaches damp blue litmus paper

Question 43

Test for hydrogen gas

Answer 43

Produces a squeaky pop near a lit splint

Question 44

Metal + acid is what

Answer 44

Salt and hydrogen