acids and alkalis

Question 1

what are acids on the pH scale

Answer 1

0-6

Question 2

what are alkalis on the pH scale

Answer 2

8-14

Question 3

what is neutral on the pH scale

Answer 3

7

Question 4

what colour are acids on the pH scale

Answer 4

red-yellow

Question 5

what colour are alkalis on the pH scale

Answer 5

blue-purple

Question 6

what colour is neutral on the pH scale

Answer 6

green

Question 7

what is neutralisation

Answer 7

reacting between acids and bases

Question 8

what do acids produce in water

Answer 8

hydrogen ions (H+)

Question 9

what do alkalis produce in water

Answer 9

hydroxide ions (OH-)

Question 10

what happens when the concentration increases + e.g.

Answer 10

pH decreases by 1

e.g. if the concentration increase by 10 the pH decreases by 1

Question 11

what forms when acids react with bases

Answer 11

salts

Question 12

acids + metal oxide —>

Answer 12

salt + water

Question 13

acids + metal hydroxide —>

Answer 13

salt + water

Question 14

acids + metal —>

Answer 14

salt + hydrogen

Question 15

acids + metal carbonate —>

Answer 15

salt + water + carbon dioxide

Question 16

how to make insoluble salts

Answer 16

to make a pure dry sample of insoluble, so you can use a precipitation reaction

you just need to pick the right to soluble salts and wrap them together to get your insoluble salt

Question 17

method for making insoluble salts

Answer 17

1. add one spatula of lead nitrate to a test tube and water to dissolve it.
2. shake it through thoroughly to ensure the lead nitrate has dissolved, then in a separate to do the same with one spatula of sodium chloride.

Question 18

making soluble salts using acid/alkali reactions

Answer 18

1. Measure out a set of acid into a conical flask, using a pipette and add a few drops of indicator.
2. slowly add alkali to the acid, using a burette, until reached endpoint – this is when the acids been exactly neutralise an indicator change of colour.
3. then carry out the reactions use exactly the same volumes of alkali and acid, but with no indicator, so the salt won’t be contaminated with indicator.
4. The solution that remains when the reaction is complete, contains only the salt and water.
5. slowly evaporate off some of the water and leave the solution to crystallise.
6. filter off the solid and dry it and you’ll be left with pure dry salt.

Question 19

what does electrolysis involve

Answer 19

oxidation and reduction

Question 20

what is electrolysis

Answer 20

breaking down of a substance using electricity. an electric current is passed through an electrolyte.

Question 21

what is oxidation

Answer 21

loss of electrons

Question 22

what is reduction

Answer 22

gain of electrons

Question 23

where does reduction happen

Answer 23

cathode

Question 24

where does oxidation happen

Answer 24

anode

Question 25

what is a half reaction

Answer 25

shows how electrons are transferred during reactions.

Question 26

how to set up a half equation

Answer 26

put one of the things being oxidised or reduced one side of the arrow and the thing it gets oxidised or reduced to on the other balance the number of atoms add electrons written e- on the side to balance charges

Question 27

how to set up a electrolysis practical

Answer 27

1. get 2 inert electrodes 2. clean the surfaces of the electrodes using some emery paper 3. do not touch with you hands 4. place both electrodes into a beaker and fill with your electrolyte 5. connect the electrodes to a power supply and turn your power supply on so a current will flow through the cell