Chemical Changes

Question 1

Neutralisation

Answer 1

A reaction between an acid and a base to produce a salt and water

Question 2

Acid

Answer 2

A substance with a pH of less than 7

The higher the concentration if the ion, the more acidic a substance is

Question 3

Base

Answer 3

A substance that reacts with an acid to produce a salt and water

Question 4

Alkali

Answer 4

A base that is soluble in water

The higher the concentration of hydroxide ions, the higher the pH

Question 5

What are the indicators of pH?

Answer 5

Litmus - red - acidic purple - neutral blue- alkaline
Methyl orange/red -acidic yellow- neutral and alkaline
Phenolphthalein - colourless- acidic+ neutral pink- alkaline

Question 6

Acid ionising

Answer 6

All acids can ionise in a solution - split into H+ ions and other ion

Question 7

Strong acids

Answer 7

Completely dissociate in water
Completely ionise in water
They have a low pH of 0-2

Question 8

Weak acids

Answer 8

Only partially dissociate in water
Do not fully ionise
pH is around 6

Question 9

What is ionisation of a weak acid!

Answer 9

A reversible reaction - sets up an equilibrium

Question 10

Concentrated

Answer 10

An acid with a large number of acid molecules compared to the volume of water
How many particles are dissolved in a given volume of liquid

Question 11

Dilute

Answer 11

A small number of acid molecules compared to the volume of water

Question 12

If a concentration of H+ ions increase by a factor of 10…

Answer 12

The pH decreases by 1

Question 13

If the H+ concentration increases by a factor of 100…

Answer 13

The pH decreases by 2

Question 14

Acid + metal oxide

Answer 14

• salt and water

Question 15

Acid + metal hydroxide

Answer 15

Salt + water

Question 16

Acid + metal

Answer 16

Salt + hydrogen

Question 17

Acid + metal carbonate

Answer 17

Salt + water + carbon dioxide

Question 18

Soluble rules in water

Answer 18

Chlorides
Sulfates
Nitrates
Sodium, potassium, ammonium hydroxide, carbonate

Question 19

Insoluble in water rules

Answer 19

Silver,lead chloride
Lead, barium, calcium sulfate
Most carbonates
Most hydroxides

Question 20

How do you make insoluble salts

Answer 20

Add two soluble salts to make insoluble salt

Question 21

The more H+ ions an acid has…

Answer 21

The lower the pH - 1/2

Question 22

The less H+ ions in an acid…

Answer 22

The higher the pH - 4/5

Question 23

Strong acids

Answer 23

Sulphuric acid
Hydrochloric acid
nitric acid

Question 24

Weak acid

Answer 24

Ethanoic acid
Citric acid
Carbonic acid

Question 25

Method for lead nitrate + sodium chloride - lead chloride +sodium nitrate

Answer 25

Add lead nitrate to test tube + add deionised water Add sodium chloride to another tube and water Mix together - lead chloride should precipitate out Filter solution - scrape lead chloride onto filter paper

Question 26

How do you make a soluble salt?

Answer 26

React an acid with an insoluble salts

Question 27

Making soluble salts method | Sulphuric acid and copper oxide

Answer 27

Add base to a liquid Filter off the excess solid Evaporate the water Allow to cool and allow salt to crystallise

Question 28

Titration method

Answer 28

Pipette and filler - transfer 25cm of aqueous sodium hydroxide into flask- add drop of phenopeliain - close tap on burette -fill hcl Record initial burette reading from meniscus Add hcl to sodium hydroxide - mix gently Record final burette reading - calculate titre and repeat 3 times

Question 29

Electrolytes

Answer 29

A molten or dissolved ionic compound

Question 30

Electrolysis

Answer 30

The breaking down of a substance using electricity | An electric current is passed through an electrolyte causing it to decompose

Question 31

Positive ions in electrolysis

Answer 31

Cations in the electrolyte move towards the cathode -negative electrode- and are reduced - gain electrons-

Question 32

Negative ions in electrolysis

Answer 32

Anions in the electrolyte move towards the anode -positive electrode- are oxidised - lose electrons This creates a flow of charge through the electrolyte

Question 33

Why can’t an ionic solid not be electrolysed?

Answer 33

The ions are in a fixed position and can’t move

Question 34

Why can molten ionic compounds be electrolysed?

Answer 34

The ions can move freely and conduct electricity

Question 35

Predicting products of electrolysis- positive metal ions

Answer 35

Reduced to metal atoms at the cathode

Question 36

Predicting products of electrolysis - negative metal ions

Answer 36

Oxidised to atoms at the cathode

Question 37

MASH

Answer 37

Metal + Acid — Salt + hydrogen

Question 38

BASHO

Answer 38

Base + Acid — Salt + Water

Question 39

CASHOCO

Answer 39

Carbonate + Acid — water+ carbon dioxide

Question 40

Examples of base

Answer 40

Any metal followed by oxide or hydroxide