C5- Chemical Changes

Question 1

What is the reactivity series?

Answer 1

A list of metals in order of their reactivity with the most reactive metals at the top and the least reactive ones at the bottom

Question 2

Order of reactivity

Answer 2

Potassium, sodium, Lithium, Calcium, magnesium, aluminium, Zinc, Iron, Tin, lead, copper, Silver, Gold

Question 3

Potassium, Sodium, Lithium, Calcium reaction with water

Answer 3

Fizz, giving off hydrogen gas, leaving an alkaline solution of metal hydroxide

Question 4

Magnesium, Aluminium, Zinc, Iron reaction with water

Answer 4

Very slow reaction

Question 5

Tin and lead reaction with water

Answer 5

Slight reaction with steam

Question 6

Copper, Silver, Gold reaction with water

Answer 6

No reaction

Question 7

Potassium, sodium, lithium reaction with dilute acid

Answer 7

Explode

Question 8

Calcium, magnesium, aluminium, zinc, iron reaction with dilute acid

Answer 8

Fizz, giving off hydrogen gas and forming a salt

Question 9

Tin and lead reaction with dilute acid

Answer 9

React slowly with warm acid

Question 10

Copper, silver, gold reaction with dilute acid

Answer 10

No reaction

Question 11

Reactivity of metals and displacement

Answer 11

A more reactive metal will displace a less reactive metal from an aqueous solution of one of its salts

Question 12

Magnesium + copper sulfate ~>

Answer 12

Magnesium sulfate + copper
This is a displacement reaction which happens because Magnesium is more reactive than copper

Question 13

Where do non metals carbon and hydrogen fit in the reactivity series?

Answer 13

Carbon is between aluminium and zinc
Hydrogen is between lead snd copper

Question 14

What needs to happen to most metals in the Earth’s crust in order for them to be used?

Answer 14

The metals need to be chemically separated from other elements

Question 15

Whether it is worth extracting a metal depends on…

Answer 15

How easy it is to extract from its ore
How much metal the ore contains
The changing demands for a particular metal

Question 16

What is chemical reduction?

Answer 16

The removal of oxygen from a compound

Question 17

Metal + acid ~>

Answer 17

Salt + hydrogen

Question 18

Salts formed when you react metals with different acids

Answer 18

Hydrochloric acid forms chlorides
Sulfuric acid forms sulfates
Nitruc acid forms nitrates

Question 19

What is a redox reaction ?

Answer 19

A reaction where reduction (gain of electrons) and oxidation (loss of electrons) both occur

Question 20

Acid + base

Answer 20

Salt + water

Question 21

Ions of group 1 metals

Answer 21

+1

Question 22

Ions of group 2 metals

Answer 22

+2

Question 23

Aluminium ion

Answer 23

+3

Question 24

Ammonium ion

Answer 24

+1 e.g NH4^+

Question 25

Transition metals ions (dependent on roman numeral)

Answer 25

E.g Copper (II) ion = +2

Question 26

Ions of group 7 non metals

Answer 26

-1

Question 27

Nitrate ions

Answer 27

-1

Question 28

Sulfate ions

Answer 28

-2

Question 29

Making salts practical (basic steps)

Answer 29

1. Add copper oxide in excess to sulfuric acid. Warm gently on a tripod and gauze 2. When the reaction is complete filter the solution to remove excess copper oxide. 3. Evaporate half the water from the solution using a water bath. Leave the solution to form crystals in a warm room for a day. 4. Pat dry if any solution remains on the crystals

Question 30

Acid + alkali

Answer 30

Salt + water

Question 31

Acid + carbonate

Answer 31

Salt + water + carbon dioxide

Question 32

What are alkalis?

Answer 32

Soluble hydroxides. An example is sodium hydroxide solution

Question 33

What are bases?

Answer 33

Substances that can neutralise acids

Question 34

What can you use to find the PH of a solution?

Answer 34

Universal indicator

Question 35

pH scale

Answer 35

0 - most acidic 7 - neutral 14 - most alkaline

Question 36

Where is pure water on the pH scale ?

Answer 36

pH 7

Question 37

What do strong acids do in solution?

Answer 37

Ionise completely

Question 38

What do weak acids do in solution?

Answer 38

Do not fully ionise in solution

Question 39

Examples of strong acids

Answer 39

Hydrochloric acid Nitric acid Sulfuric acid

Question 40

Examples of weak acids

Answer 40

Ethanoic acid Citric acid Carbonic acid

Question 41

Concentration of Hydrogen ions (H+) in relation to pH values

Answer 41

As the concentration decreases by a factor of 10 the pH value increases by one unit e.g 0.10 to 0.010 1 to 2 on pH scale