Chemical

Question 1

How to decide if a substance is an acid or alkali

Answer 1

Depends on type of ions released when substance is dissolved in water.
Acids from hydrogen ions (H+) when dissolved in water.
Alkalis form hydroxide ions (OH-)

Question 2

Neutralisation

Answer 2

Acid + Alkali -> Salt + Water
Can be shown in terms of H+ and OH- ions.
H+ + OH- -> H2O

Question 3

Acid Strength

Answer 3

Proportion of acid particles that’ll dissociate to produce H+ ions in a solution

Question 4

Strong Acids

Answer 4

An acid (sulphuric, hydrochloride and nitrate acid) that completely dissociates its H+ ions in water (irreversible)

HCl(g) + H2O(aq) -> H+ (aq) + Cl- (aq)

Question 5

Reactions of acid

Answer 5

A base if a substance that can accept a hydrogen ion (H+) from another substance. Usually metal oxides or metal hydroxides

Question 6

Acid + Base -> ? + ?

Answer 6

Salt + water

Question 7

Metal Carbonate + acid -> ? + ? + ?

Answer 7

Metal salt + carbon dioxide + water

Metal carbonates are also bases, react with acids to produce carbon dioxide

Question 8

Acid + Metal -> ? + ?

Answer 8

Salt + Hydrogen

Question 9

Reactivity series

Answer 9

Potassium 
Sodium
Lithium
Calcium
Magnesium
Aluminium 
Zinc
Iron 
Tin 
Lead
Copper 
Mercury 
Silver 
Gold

Question 10

Why are carbon and hydrogen included in the reactivity series?

Answer 10

They’re used to displace metals from their ores

Question 11

What does the reactivity series show?

Answer 11

How easily a metal loses an electron and becomes a positive ion

Question 12

What reactions give evidence of reactivity?

Answer 12

Metal + Acid -> salt + hydrogen

Metal + water -> metal hydroxide + hydrogen

Question 13

Displacement reactions

Answer 13

Metal A + Metal B compound -> Metal B + Metal A compound

A more reactive metal displaces a less reactive metal from its compound

2HCl + Mg -> MgCl2 + H2

Question 14

atom + metal oxide ->? What

Answer 14

Salt + water

Question 15

Acid + metal hydroxide ->?

Answer 15

Salt + water

Question 16

Explain an experiment for making pure salt

Answer 16

Heat sulphuric acid
Stir in copper oxide, until in excess
Let it cool
Filter the solution to remove the excess copper oxide
Evaporate away the liquid 

Equation:
Sulphuric acid + Copper oxide -> Copper sulphate + water

H2SO4 + CuO -> CuSO4 + H2O

Question 17

What does 1 mean on the pH scale?

Answer 17

Acid

Question 18

What number represents neutral on the pH scale?

Answer 18

Neutral

Question 19

What number represents Alkali on the pH scale?

Answer 19

14

Question 20

Neutralisation Equation

Answer 20

H+ + OH- reversible arrows H2O

Question 21

How do cells work?

Answer 21

Example:
Copper in copper sulphate solution
Zinc in Zinc sulphate solution
Salt bridge between
Zinc is high up in the reactivity series so pushes electrons making a potential difference
Zn-> Zn2+ + 2e-
Cu2+ + 2e- -> Cu

Question 22

Non rechargeable batteries

Answer 22

The reactants that produces electricity ones it’s used up its dead

Question 23

Rechargeable batteries

Answer 23

Reversible
Once reactants used up, electricity can pass through causing the reaction to go in reverse direction, recharging reactants

Question 24

Hydrogen fuel cell

Answer 24

Hydrogen gas reacts with oxygen gas, turning into water
Advantages
Energy released
Water is only product- no carbon emissions

Disadvantages 
Production of hydrogen uses fossil fuels
Not sold everywhere
Hydrogen needs to be compressed
Explosive
Large tank to store
Don’t work at low temp

Question 25

Half equations for hydrogen fuel cell

Answer 25

Negative electrode
H2 - 2e- -> 2H+

Positive electrode
4H+ + O2 + 4e- -> 2H2O