C4 - Chemical Changes

Question 1

What is a displacement reaction

Answer 1

When a more reactive metal displaces a less reactive metal from a compound

Question 2

Metal + Acid ——>

Answer 2

Salt + Hydrogen

Question 3

Metal carbonate + acid —->

Answer 3

Salt +Carbon dioxide + water

Question 4

Group 1 metals are ____reactive than hydrogen, so _____ it to produce hydrogen gas and a metal ______

Answer 4

More, displace , hydroxide

Question 5

What happens in a blast furnace?

Answer 5

Iron oxide is reduced to form iron via a displacement reaction

Question 6

We can use displacement reactions to

Answer 6

Obtain metals from their ores

Question 7

Order of the reactivity series
(Please Stop Calling Me A Careless Zebra Instead Try Learning How Copper Saves Gold)

Answer 7

Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold
Platinum

Question 8

OIL RIG stands for

Answer 8

Oxidation is loss (of electrons)
Reduction is gain (of electrons)

Question 9

What is neutral on the pH scale?

Answer 9

7

Question 10

What is more acidic on the pH scale

Answer 10

Below 7

Question 11

What is more alkaline on the pH scale

Answer 11

More than 7

Question 12

Why does an acid of a low pH

Answer 12

It is due to its H+ ions

Question 13

Why does an alkaline have a pH above 7

Answer 13

Due to its OH- ions

Question 14

pH is dependent on the concentration of

Answer 14

H+ or OH- ions

Question 15

A change of 1 pH is a ____ change of concentration of ___ or ____ ions

Answer 15

10x change in concentration of H+ or OH- ions

Question 16

pH also depends on how _____/______ an acid is

Answer 16

Strong/weak

Question 17

A strong acid will __________ more completely than a weak acid

Answer 17

Dissociate

Question 18

3 examples of strong acids

Answer 18

Hydrochloric
Sulphuric
Nitric

Question 19

3 examples of weak acids

Answer 19

Ethanoic
Citric
Carbonic

Question 20

What do we use to measure what volume of acid/alkali is needed to neutralise

Answer 20

Burette

Question 21

Method of titration

Answer 21

-Measure 50cm3 of alkali of known concentration using a glass pipette and put it in a conical flask with PHENOLPHTHALEIN indicator
-Place flask on a white tile underneath the tap of burette
—Put acid of unknown concentration in burette (up to 0cm3 mark), open the tap and let it drip into flask
—Once the solution in the flask turns pink, stop and swirl the concicql flask
-If it goes colourless then neutralisation has occurred
-use moles to calculate the unknown concentration of the acid
-

Question 22

Define electrolysis

Answer 22

Passing an electrical current through a substance to cause oxidation and reduction at two electrodes

Question 23

What happens at the anode

Answer 23

Oxidation

Question 24

What happens at the cathode

Answer 24

Reduction

Question 25

Electrolysis can only happen if ions are

Answer 25

Free to move to the electrode that they are attracted to

Question 26

Why can’t electrolysis take place for solids

Answer 26

Ions are not free to move

Question 27

During electrolysis of molten aluminium oxide why does the graphite anode need to be replaced regularly

Answer 27

Oxygen reacts with the carbon in the graphite anode to create carbon dioxide gas

Question 28

Why do we use cryolite during electrolysis of molten aluminium oxide

Answer 28

Lowers the boiling point of aluminium oxide, so it is cheaper

Question 30

During electrolysis of molten aluminium oxide, O2- ions are attracted to the ______ and are oxidised to form O2

Answer 30

Anode

Question 32

Half equation at the anode during electrolysis of aluminium oxide

Answer 32

O2- —-> O2 + 4e-

Question 33

Half equation at the cathode during electrolysis of molten aluminium oxide

Answer 33

Al3+ + 3e- —-> Al

Question 34

Why can electrolysis take place in solutions

Answer 34

Ions are free to move to the electrodes

Question 35

If a halide ion is present during electrolysis of solutions then it is always

Answer 35

Oxidised at the anode

Question 36

If there is no halide ion in the electrolysis of a solution then _____ is oxidised at the anode instead

Answer 36

Oxygen

Question 37

The ____ reactive cation ( + ion) remains in solution and the ____ reactive one is reduced at the cathode. ( If the cation is less reactive than hydrogen it will be formed at the cathode, if not hydrogen will be )

Answer 37

More Less

Question 38

Acid + Alkali —->

Answer 38

Salt + Water

Question 39

Sulphuric acid + metal —->

Answer 39

Metal sulphate

Question 40

Nitric acid + metal

Answer 40

Metal nitrate