Acids & Alkalis F4

Question 1

Definition of an indicator

Answer 1

An indicator is a chemical which is one colour in acid and another in alkali

Question 2

Red litmus in acid

Answer 2

Stays red

Question 3

Red litmus in alkali

Answer 3

Turns blue

Question 4

Blue litmus in acid

Answer 4

Turns red

Question 5

Blue litmus in alkali

Answer 5

Stays blue

Question 6

Phenolphalein in acid

Answer 6

Stays colourless

Question 7

Phenolphalein in alkali

Answer 7

Turns pink

Question 8

Methyl Orange in acid

Answer 8

Turns pink

Question 9

Methyl Orange in alkali

Answer 9

Turns yellow

Question 10

Advantages of an indicator

Answer 10

• Shows different colours for acids and alkalis

Question 11

Disadvantages of an indicator

Answer 11

• Don’t tell us relative strengths

- Limited in their use

Question 12

Universal indicators

Answer 12

Indicate the STRENGTH of the substance

Question 13

pH of strong acid

Answer 13

0 - 2

Question 14

pH of weak acid

Answer 14

3 - 6

Question 15

pH of weak alkali

Answer 15

8 - 11

Question 16

pH of strong alkali

Answer 16

12 - 14

Question 17

Strong Acids

Answer 17

• Hydrochloric Acid
• Nitric Acid
• Sulfuric Acid

Question 18

Weak Acids

Answer 18

• Ethanoic Acid

- Carbonic Acid

Question 19

Neutral Substances

Answer 19

• Water
• Petrol
• Ethanol

Question 20

Weak Alkalis

Answer 20

• Ammonia

Question 21

Strong Alkalis

Answer 21

• Sodium Hydroxide

- Potassium Hydroxide

Question 22

Definition of an acid

Answer 22

Substance which dissolves in water to produce HYDROGEN IONS.

Question 23

What is a strong acid?

Answer 23

One which is completely ionised in water and contains a high concentration of Hydrogen ions.

Question 24

What is a weak acid?

Answer 24

One which is partially ionised in water and contains a low concentration of Hydrogen ions.

Question 25

Definition of an alkali

Answer 25

A soluble base which dissolves in water to produce HYDROXIDE IONS.

Question 26

What is a weak alkali?

Answer 26

One which is partially ionised in water

Question 27

Definition of a base

Answer 27

Metal oxide or metal hydroxide

Question 28

Definition of concentration

Answer 28

How much of the original acid is dissolved in the solution

Question 29

Definition of neutralisation

Answer 29

Reaction between hydrogen ions of an acid and hydroxide ions of an alkali to produce water

Question 30

METAL + ACID

Answer 30

SALT + HYDROGEN (MASH)

Question 31

ACID + METAL OXIDE (base) =

Answer 31

SALT + WATER

Question 32

ACID + CARBONATE =

Answer 32

SALT + WATER + CARBON DIOXIDE

Question 33

ACID + HYDROGEN CARBONATE =

Answer 33

SALT + WATER + CARBON DIOXIDE

Question 34

ACID + AMMONIA =

Answer 34

AMMONIUM SALT

Question 35

Copper (II) Oxide colour and in solution

Answer 35

Black - (-)

Question 36

Copper (II) Carbonate colour and in solution

Answer 36

Green - (-)

Question 37

Copper (II) Sulfate colour and in solution

Answer 37

Blue - (-)

Question 38

Group 1 / 2, Al & Zn compounds

Answer 38

White - Colourless

Question 39

METAL + ACID Observations

Answer 39

- Heat - Effervescence - Metal disappears - Colourless solution

Question 40

ACID + (HYDROGEN) CARBONATE Observations

Answer 40

- Heat - Effervescence - Metal (hydrogen) carbonate disappears - Solution produced (coloured - transition metal) (clear - group 1 & 2)

Question 41

Test for Hydrogen

Answer 41

Lighted splint on mouth of test tube with Hydrogen gas burns in air with squeaky pop

Question 42

Test for Carbon Dioxide

Answer 42

Bubble Carbon Dioxide through limewater. Limewater turns from colourless to milky white.

Question 43

What is an endothermic reaction?

Answer 43

A reaction that takes in heat.

Question 44

What is an exothermic reaction?

Answer 44

A reaction that gives out heat. (all neutralisation reactions)

Question 45

What is a calorimeter?

Answer 45

Experimental apparatus used to measure temperature.

Question 46

What is a Salt?

Answer 46

A compound formed when some / all of the hydrogen ions in an acid are replaced by metal ions.

Question 47

Soluble Salts from Insoluble Bases / Acids

Answer 47

- 25cm of acid into conical flask - warm acid & add metal oxide until saturated - filter mixture - heat solution - leave to cool

Question 48

Soluble Salts from Soluble Bases / Alkalis

Answer 48

- fill burette with dilute acid - pipette 25cm alkali to conical flask - 3 drops of phenolphalein - add acid from burette and mix - stop adding acid at end point (pink to colourless) - record volume of acid added

Question 49

ALTERNATIVE PROCEDURE for Soluble Bases / Alkalis

Answer 49

- repeat titration with fresh samples of alkali until 2 concordant results are obtained - repeat titration without indicator - heat in evaporating basin - leave to cool

Question 50

Chemical equation for Hydrogen

Answer 50

Hydrogen + oxygen = water