Acids and Alkalis

Question 1

On a hazard card, what would the picture look like to show that something is poisonous?

Answer 1

A skull and cross bones

Question 2

On a hazard card, what would the picture look like to show that something is corrosive?

Answer 2

A hand with a burn mark on it.

Question 3

Kitchen cleaners that are able to remove limescale and make surfaces shiny contain an acid that is usually around pH 2, is this a strong or weak acid?

Answer 3

Strongly acidic - Red on the pH scale

Question 4

What is the colour of a solution that is pH 7?

Answer 4

Green

Question 5

bicarbonate of soda is an alkaline, what colour would it turn universal indicator?

Answer 5

blue

Question 6

What gas is produced when bicarbonate is added to acid?

Answer 6

carbon dioxide

Question 7

How can you test for carbon dioxide?

Answer 7

Bubble through limewater, it will turn milky/cloudy if carbon dioxide is present.

Question 8

What is the chemical name for limestone?

Answer 8

calcium carbonate

Question 9

What acid would you use to make zinc sulphate?

Answer 9

sulphuric acid

Question 10

acid + alkali ->

Answer 10

salt + water

Question 11

acid + metal oxide ->

Answer 11

salt + water

Question 12

acid + metal ->

Answer 12

salt + hydrogen

Question 13

acid + metal carbonate ->

Answer 13

salt + water + carbondioxide

Question 14

How would you know a gas had been given off in a reaction?

Answer 14

Bubbles are formed

Question 15

How do you test for hydrogen

Answer 15

lighted splint goes pop

Question 16

How can you obtain crystals from a salt solution?

Answer 16

evaporate the water

Question 17

Hydrochloric acid will make what type of salt?

Answer 17

chloride

Question 18

sodium hydroxide + hydrochloric acid ->

Answer 18

sodium chloride + water

Question 19

When making copper chloride, you add lots of copper oxide to hydrochloric acid. How do you remove the unreacted copper oxide?

Answer 19

filter it using filter paper and a funnel.

Question 20

When making copper chloride, why do you add more copper oxide that you need?

Answer 20

To make sure all the hydrochloric acid has been neutralised.

Question 21

Some metals do not react with acid, can you name one?

Answer 21

copper - unreactive in acid

Question 22

What is displacement?

Answer 22

a more reactive metal will displace (take the place of) a less reactive metal in a salt solution.

Question 23

iron + copper sulphate ->

Answer 23

iron sulphate + copper (iron is more reactive, so displaces copper)

Question 24

copper + zinc sulphate ->

Answer 24

no change. (zinc is more reactive that copper so copper is unable to displace it from its salt)

Question 25

name metals more reactive than iron

Answer 25

zinc, magnesium, calcium are a few.

Question 26

How do you carry out a titration?

Answer 26

A pipette is used to measure accurately a volume of acid - for example, 10cm3. This is emptied into a conical flask. A few drops of an indicator may be added to the conical flask. This will show a change of colour when the titration is complete. The burette is filled with an alkali. The solution from the burette is run into the conical flask. The solution is added one drop at a time, with swirling to mix the solutions as the end-point is approached. Eventually, a colour change shows that the correct amount has been added to react completely with the acid. It is now neutral. Measure the volume of alkali that was needed.