Chemistry Chemical Changes March 2018

Question 1

What is the most reactive metal?

Answer 1

Potassium

Question 2

What is the least reactive metal?

Answer 2

Platinum

Question 3

What metals do not react with oxygen?

Answer 3

Silver, Gold and Platinum

Question 4

What metals react with water?

Answer 4

Potassium, Sodium, Lithium, Calcium and Magnesium

Question 5

What metals react violently with acids?

Answer 5

Potassium, Sodium and Lithium

Question 6

What metals react normally with acids?

Answer 6

Calcium, Magnesium and Aluminium

Question 7

What metals react slowly with acids?

Answer 7

Zinc, Iron, Tin and Lead

Question 8

What metals don’t react with acids?

Answer 8

Copper, Silver, Gold and Platinum

Question 9

Metal + Oxygen = ?

Answer 9

Metal Oxide

Question 10

Metal + Water = ?

Answer 10

Metal Hydroxide + Hydrogen

Question 11

Metal + Acid + ?

Answer 11

Metal Salt + Hydrogen

Question 12

What is an example of a salt?

Answer 12

Potassium + Hydrochloric acid = Potassium Chloride + Hydrogen

Question 13

What is the definition of oxidation?

Answer 13

Oxidation - A reaction where a substance loses
electrons.
Reduction - A reaction where a substance gains
electrons.
Mnemonic -
OIL RIG

O - Oxidation
I - Is
L - Loss of electrons

R - Reduction
I - Is
G - Gain of electrons

Question 14

Where is carbon on the reactivity scale? Hydrogen?

Answer 14

Carbon - Between Aluminium and Zinc (7th from top)
Hydrogen - Between Lead and Copper (5th from
bottom)

Question 15

What is a displacement reaction?

Answer 15

A reaction where a more reactive element takes the place of a less reactive element in a compound.

Question 16

What is a redox reaction?

Answer 16

A reaction where both reduction and oxidation takes place.

e.g 2Al+Fe2O3 –> Al2O3+2Fe

Question 17

What are acids and alkalis?

Answer 17

Acid - A solution with a pH less than 7; produces H+
ions in water.
Alkali - Solution with a pH more than 7; produces OH-
ions in water.
(pH of 7 is neutral)

Question 18

What is the difference between strong and weak acids?

Answer 18

Strong - An acid in which all the molecules break into
ions in water.
Weak - An acid in which only a small fraction of
molecules break into ions in water.

Question 19

What is a salt?

Answer 19

• A substance made when acids react with metals,
  metal hydroxides, metal oxides and metal carbonates.
• Found in many medicines, fertilisers, toothpaste and
  food additives.

Question 20

What is electrolysis?

Answer 20

The decomposition of ionic compounds using electricity.

Question 21

What are the electrodes? What is an electrolyte?

Answer 21

Anode - An electrode where oxidation takes place. In
electrolysis it is the positive electrode.
Cathode - An electrode where reduction takes place. In
electrolysis it is the negative electrode.
Electrolyte - A liquid that conducts electricity.

Question 22

What is discharge (of ions)?

Answer 22

The gain or loss of electrons to become electrically neutral.

Question 23

What are ionic equations and half equations?

Answer 23

Ionic - An equation that shows all ionic charges in a
reaction not including ones that do not change.
(Cu + 2Ag+ –> Cu2+ + 2Ag)
Half - An equation that shows the gain or loss of
electrons to an ion. (Ag+ + e- –> Ag)

‘Original equation = Cu + 2AgNO3 –> Cu(NO3)2 + 2Ag’