Acids, Bases And Salts

Question 1

What colours do litmus solution go in acid, neutral and alkaline?

Answer 1

Acid: pale red
Neutral: purple
Alkaline: blue

Question 2

What colours does red litmus paper go in acid, neutral and alkaline?

Answer 2

Acid: red
Neutral: stays red
Alkaline: blue

Question 3

What colours does blue litmus paper go in acid, neutral and alkaline?

Answer 3

Acid: red
Neutral: stays blue
Alkaline: blue

Question 4

What colours does phenolphthalein go in acid, neutral and alkaline?

Answer 4

Acid: colourless
Neutral: colourless
Alkaline: pink

Question 5

What colours does methyl orange go in acid, neutral and alkaline?

Answer 5

Acid: red
Neutral: orange
Alkaline: yellow

Question 6

What colours does universal indicator go in acid, neutral and alkaline?

Answer 6

Acid: red
Neutral: green
Alkaline: purple

Question 7

What causes acidity?

Answer 7

The H+ ion

Question 8

What does the pH scake measure?

Answer 8

Concentration of H+ ions
Is a logarithmic scale, like richter scale, so pH 1 contains 10x more H+ ions than pH 2, and 100x more than a pH of 3

Question 9

What is a more accurate measure of finding out pH?

Answer 9

A pH meter

Question 10

Define an arrhenius acid

Answer 10

An acid that dissolves into water to form hydrogen ions

Question 11

What is the difference between calling an acid concentrated/dilute and calling an acid strong/weak

Answer 11

A concentrated acid is where there is lots of acid molecules dissolved into water
BUT
A strong acid is where lots of acid molecules have disassociated into H+ ions

Question 12

What is it called when an acid dissolves into water and splits up into H+ and another ion?

Answer 12

Disassociation, or ionisation

Question 13

What does the reversible arrow show?

Answer 13

Reaction does not go to completion, only some molecules ionise

Question 14

Acids are weak if…..?

Answer 14

Few molecules ionise/dissociate

Question 15

Define bases

Answer 15

A substance that can neutralise acids

Question 16

Examples of bases?

Answer 16

Metal oxides and hydroxides

Question 17

What are alkalis?

Answer 17

Bases that are soluble in water

(Ususally soluble metal hydroxides)

Question 18

What is produced if a reactive metal and acid react?

Answer 18

Reactive metal + acid -> metal salt + hydrogen

Question 19

What is produced if a base (alkali) reacts with an acid?

Answer 19

Base/alkali + acid -> metal salt + water

Question 20

What happens if a metal carbonate reacts with an acid?

Answer 20

Metal carbonate + acid -> metal salt + water + carbon dioxide

Question 21

What happens if ammonia reacts with an acid?

Answer 21

Ammonia + acid -> Ammonium salts

Question 22

When making ionic equations, what is seperable, and what is inseparable?

Answer 22

Seperable
- acids
- ionic compounds

Inseperable
- elements
- covalent compounds

Question 23

General form of an ionic equation of acid + hydroxide?

Answer 23

H+ + OH‐ -> H²O

Question 24

General form of an ionic equation of acid + hydroxide?

Answer 24

H+ + OH‐ -> H²O

Question 25

General form of an ionic equation of acid + ammonia?

Answer 25

H+ + NH³ -> NH⁴

Question 26

How do you show something is hydrated?

Answer 26

With the • symbol, eg CuSO⁴ • 5H²O

Question 27

What is the test for water?

Answer 27

Anhydrous CuSO⁴ goes from white to blue Or Cobalt chloride paper goes from blue to pink

Question 28

What type of scale is the pH scale?

Answer 28

Logarithmic

Question 29

Symbol for phosphoric acid?

Answer 29

H³PO⁴

Question 30

Symbol for ethanoic acid?

Answer 30

CH³COOH

Question 31

Symbol for carbonic acid

Answer 31

H²CO³

Question 32

What happens in a neutralisation reaction?

Answer 32

H+ ions from acid combine with OH- ions from alkali to form neutral H²O

Question 33

When to use excess base method?

Answer 33

Base is soluble and salt produced is soluble

Question 34

How to carry out excess base method?

Answer 34

1. Combine base and acid, with excess amounts of base 2. Once reaction complete, Filter out excess base 3. Heat to evaporates off ~ ⅔ solution to make it saturated, making sure not to boil off all water as this will create anhydrous crystals 4. Leave to cool and crystallise

Question 35

What does anhydrous mean, and how can you convert hydrated crystals into anhydrous ones?

Answer 35

No water trapped in it. Hydrated can be converted into anhydrous by heating to evaporates water out.

Question 36

When to use titration?

Answer 36

Soluble base -> soluble salt

Question 37

Procedure for titration?

Answer 37

1. Use glass Pipette to measure exactly 25cm³ alkali into conical flask with a few Drops of indicator 2. Put acid onto burette, and add to alkali slowly. Once it is nearly neutralised, add acid 1 drop at a time until indicator changes colour. Record volume of acid added from burette. 3. Repeat whole Experiment again but without indicator 4. Heat salt solution, evaporates some of the water away to make a saturated solution 5. Leave to cool and crystallise

Question 38

When to use precipitation method?

Answer 38

Soluble base -> insoluble salt

Question 39

Procedure for precipitation method?

Answer 39

1. Choose 2 suitable soluble solutions (Generally metal nitrate and sodium compond) 2. Combine solutions and Filter the solution 3. Wash precipitate with distilled water to remove impurities 4. Leave to dry

Question 40

What are the solubility rules for salts?

Answer 40

SOLUBLE CANS ARE SOLUBLE Chlorides ( except Ag and Pb) All Na, K and NH⁴ salts Nitrates Sulphates ( except Ba, Pb and Ca ) INSOLUBLE Carbonates ( except Na, K and NH⁴) Hydroxides ( except Na, K and NH⁴)

Question 41

How to choose which salt production method to use?

Answer 41

Insoluble salt: precipitation method Soluble salt, but not Na, K or NH⁴ : excess base method Soluble salt that is Na, K or NH⁴ : titration method

Question 42

Which method does not require an acid?

Answer 42

Precipitation