Chemistry GCSE Acids and Alkalis

Question 1

What colour will litmus solution be in an acid?

Answer 1

red

Question 2

What colour will litmus solution be in an alkali?

Answer 2

purple/blue

Question 3

What colour will litmus solution be in a neutral substance?

Answer 3

purple

Question 4

What colour will phenolphthalein be in an acid?

Answer 4

colourless

Question 5

What colour will phenolphthalein be in an alkali?

Answer 5

pink

Question 5

What colour will phenolphthalein be in a neutral substance?

Answer 5

colourless

Question 6

What colour will methyl orange be in an acid?

Answer 6

pinkish red

Question 7

What colour will methyl orange be in an a neutral substance?

Answer 7

orange

Question 8

What colour will methyl orange be in an alkali?

Answer 8

yellow

Question 8

What colour will methyl orange be in an alkali?

Answer 8

yellow

Question 9

What colour will universal indicator be in an acid?

Answer 9

red/orange

Question 10

What colour will UI be in an alkali?

Answer 10

purple/blue

Question 11

What colour will UI be in a neutral substance?

Answer 11

green

Question 12

How do litmus papers change in different pHs?

Answer 12

red litmus paper turns blue in an alkali, and vice-versa

Question 13

What causes acidity?

Answer 13

the H+ ion

Question 14

What is the pH scale?

Answer 14

A measure of the concentration of H+ ions in a solution, and hence its acidity.

Question 15

What does pH stand for?

Answer 15

p- potenz, german word for power
H- (hydrogen)

Question 16

what type of scale is the pH scale?

Answer 16

logarithmic

Question 17

how many more times the amount of hydrogen does a pH-1 acid have than a pH-2 acid?

Answer 17

ten times

Question 18

What is the name of the equipment you can use to measure a substance’s pH?

Answer 18

a pH probe or pH meter

Question 19

How are solutions of acids made?

Answer 19

specific covalent molecules dissolved in water,which causes the molecules to break apart, generating hydrogen ions

Question 20

What do the words concentrated and dilute refer to, in terms of acids?

Answer 20

The amount of acid molecules dissolved in water. A concentrated acid will have a large amount of acid molecules dissolved in a certain amount of water, and vice-versa

Question 21

What do the words strong and weak refer to, in terms of acids?

Answer 21

The amount of the acid molecules that have been split apart into ions.

Question 21

What is dissociation?

Answer 21

acid molecules splitting into ions

Question 21

What is ionisation?

Answer 21

acid molecules splitting to ions

Question 22

What is another word for dissociation?

Answer 22

ionisation

Question 23

What makes an acid a strong one?

Answer 23

It will completely dissociate into ions in water- all of the molecules will have broken apart to form hydrogen ions.

Question 24

Give some examples of strong acids

Answer 24

Hydrochloric acid, nitric acid and sulphuric acid

Question 25

What makes an acid a weak one?

Answer 25

Only a small proportion of the molecules will have dissociated into ions. The solution mostly contains undissociated molecules, and a low number of ions

Question 26

Give an example of a weak acid

Answer 26

ethanoic acid

Question 27

What is the formula for ethanoic acid?

Answer 27

CH₃COOH

Question 28

What is a base?

Answer 28

A substance that can neutralise an acid, soluble or not

Question 29

What is an alkali?

Answer 29

A soluble base/a substance that releases OH- ions when dissolved

Question 30

what causes alkalinity?

Answer 30

the OH- ion

Question 31

Give some examples of strong alkalis

Answer 31

Sodium hydroxide and potassium hydroxide

Question 32

Give an example of a weak alkali

Answer 32

ammonia

Question 33

What is the product of a reaction between a reactive metal and an acid?

Answer 33

metal salt + hydrogen

Question 34

What is the product of a reaction between a base and an acid?

Answer 34

metal salt + water

Question 35

What is the product of a reaction between a metal carbonate and an acid?

Answer 35

metal salt + water + CO2

Question 36

What is the product of a reaction between ammonia and an acid?

Answer 36

an ammonium salt

Question 37

if the end result of a reaction was an ammonium salt, what were the reactants?

Answer 37

ammonia + an acid

Question 38

if the end result of a reaction was a metal salt and hydrogen, what were the reactants

Answer 38

reactive metal + acid

Question 39

if the end result of a reaction was water and a metal salt, what were the reactants?

Answer 39

base + acid

Question 40

give four examples of non reactive metals

Answer 40

Gold, silver, platinum, copper

Question 41

How do you write an ionic equation?

Answer 41

1) write balanced equation 2) rewrite equation separating out ions in the compounds and the acid. covalent compounds stay unseparated 3)cancel ions that appear on either side 4)write the ionic equation

Question 42

What is the name of the ion that you remove to make an ionic equation?

Answer 42

spectator ion

Question 43

How do you do the excess base method?

Answer 43

add excess base 2 acid filter out insoluble base heat the filtrate to evaporate most but not all water, you do not want it to be anhydrous

Question 44

When do you use the excess base method?

Answer 44

When the base is insoluble, and the salt is soluble

Question 45

When should you use titration?

Answer 45

When you start with an alkali and finish with a soluble salt

Question 46

When should you use precipitation?

Answer 46

When you start with an alkali and finish with an insoluble salt

Question 47

What is titration?

Answer 47

When two solutions are carefully mixed to determine the exact volumes of each which react together

Question 48

What do you call the moment in titration when the reaction is complete?

Answer 48

the end-point

Question 49

What equipment do you need for titration?

Answer 49

(among other things) a pipette and a burette

Question 50

What are the solubility rules surrounding sodium salts?

Answer 50

All are soluble

Question 51

What are the solubility rules surrounding potassium salts?

Answer 51

All are soluble

Question 52

What are the solubility rules surrounding ammonium salts?

Answer 52

All are soluble

Question 53

What are the solubility rules surrounding nitrates?

Answer 53

All are soluble

Question 54

What are the solubility rules surrounding carbonates?

Answer 54

All are insoluble, except group 1 + NH4

Question 55

What are the solubility rules surrounding hydroxides?

Answer 55

All are insoluble, except group 1+ NH4

Question 56

What are the solubility rules surrounding chlorides?

Answer 56

All are soluble except silver and lead

Question 57

What are the solubility rules surrounding sulphates?

Answer 57

All are soluble, except barium, lead and calcium sulphates

Question 58

What is an acid?

Answer 58

A substance that releases H+ ions when dissolved in water

Question 59

Why should potassium sulphate not be made from the reaction between potassium and sulphuric acid?

Answer 59

As a group 1 metal, potassium is highly reactive so such a reaction would be dangerous

Question 60

Why could copper sulfate not be made from a reaction between copper and sulphuric acid?

Answer 60

Copper is not reactive enough

Question 61

Give a detailed method for making a pure sample of the salt nickel chloride frim nickel oxide (insoluble base) (Four marks)

Answer 61

-Add HCl to NiO -Add excess NiO -Filter off NiO -Evaporate water

Question 62

why do you use a burette in titration? (2 points)

Answer 62

it is an accurate way to measure a substance which measures variable volumes- you don't know how much it will be

Question 63

in titration, you repeat until you have...

Answer 63

concordant results