Chemistry P1 - Chemical Changes

Question 1

Which two reactions are examples of oxidisation?

• sodium carbonate —-> sodium oxide + carbon dioxide
• magnesium + oxygen —-> magnesium oxide
• mercury oxide —-> mercury + oxygen
• zinc + oxygen —-> zinc(II) oxide

Answer 1

• magnesium + oxygen —-> magnesium oxide
• zinc + oxygen —-> zinc(II) oxide

Question 2

Metals react with oxygen to produce metal _______
This reaction is called ______

Answer 2

• oxides
• oxidation

Question 3

What are the products of the reaction of potassium with water?

Answer 3

potassium hydroxide + hydrogen

Question 4

_______ + sulfuric acid —-> magnesium sulfate + ________

Answer 4

magnesium
hydrogen

Question 5

List the reactivity series

Answer 5

Potassium
Sodium
Calcium
Magnesium
Aluminium
CARBON
Zinc
Iron
Tin (Sn)
Lead (Pb)
HYDROGEN
Copper (Cu)
Mercury (Hg)
Silver (Ag)
Gold (Au)

Question 6

What are electrodes in electrolysis?

Answer 6

Solid conductors (metal or carbon)

Question 7

What is an electrolyte in electrolysis?

Answer 7

The liquid or solution that contains and ionic compound (ions are free to move)

Question 8

What do you have to do if the electrolyte is soluble?

Answer 8

Nothing

Question 9

What do you have to do if the electrolyte is insoluble?

Answer 9

• Melt it (why?)
• So the ions are free to move

Question 10

What is the positive electrode called?

Answer 10

The anode

Question 11

What is the negative electrode called?

Answer 11

The cathode

Question 12

What must be connected to the anode and cathode and why?

Answer 12

A wire (so electrons can flow) connected to a power supply (to drive the flow of electrons)

Question 13

What does the word electrolysis mean

Answer 13

Splitting up with electricity

Question 14

Which electrode will a negative ion be attracted to and what will it become?

Answer 14

• The anode
• Charged ion (-) —-> neutral atom

Question 15

Which electrode will a positive ion be attracted to and what will it become?

Answer 15

• The cathode
• Charged ion (+) —-> neutral atom

Question 16

Has a negative ion gained or lost electrons?

Answer 16

Gained

Question 17

Has a positive ion gained or lost electrons?

Answer 17

Lost

Question 18

Which two of the following chemical processes are used to extract metals from their ores?

• Thermal decomposition
• Electrolysis
• Reduction with carbon

Answer 18

• Electrolysis
• Reduction with carbon

Question 19

What do elements have to be to be able to be reduced with carbon?

Answer 19

Less reactive than carbon

Question 20

How do you extract metals that are more reactive than carbon

Answer 20

Electrolysis

Question 21

How do you extract metals that are less reactive than carbon

Answer 21

Reduction with carbon

Question 22

Why wouldn’t you want to use electrolysis?

Answer 22

• Uses lots of energy
• Expensive

Question 23

What does electrolysis do?

Answer 23

Separate ionic compounds into their pure elements

Question 24

What is aluminium found as in the earth?

Answer 24

Bauxite (aluminium oxide)

Question 25

Why do we mix aluminium oxide with cryolite before electrolysis?

Answer 25

Because it lower s the melting point

Question 26

What charge will a metal ion always have?

Answer 26

Positive

Question 27

What charge do metal and non-metal ions have in an ionic compound?

Answer 27

Metal - positive (loses electrons) Non-Metal - negative (gain electrons)

Question 28

What will happen to the metal ion in electrolysis?

Answer 28

It will collect at the cathode as a solid/liquid

Question 29

What will happen to the NON-metal ion in electrolysis?

Answer 29

It will collect at the anode and escape as a gas

Question 30

Which elements for diatomic molecules? (at the anode)

Answer 30

Hydrogen, Nitrogen, Flourine, Oxygen, Iodine, Chlorine, Bromine Have no fear of ice cold bear

Question 31

What does OIL RIG mean?

Answer 31

Oxidation Is Loss (of electrons) Reduction Is Gain (of electrons)

Question 32

What are most metal oxides?

Answer 32

Insoluble

Question 33

What is the rule for whether the H^+ ion or the metal^+ ion will be discharged at the cathode in an aqueous solution?

Answer 33

The ion of the least reactive element will be discharged

Question 34

What is the rule for what ion is discharged at the anode?

Answer 34

- If a halide is present it is discharged - If a halide is not present, the hydroxide is discharged

Question 35

What would be discharged at the anode and cathode if the electrolyte was NaCl (aq)?

Answer 35

Cathode - Hydrogen (Na is more reactive) Anode - Cl (It is a halide)