Acids and Bases

Question 1

What are the 3 physical properties of acids?

Answer 1

1. Acids have a sour taste.
2. Acids are electrolytes. They ionise to form mobile ions when dissolved in water, which act as mobile charge carriers to conduct electricity.
3. Acids have a pH of below 7. (turn blue litmus paper red).

Question 2

What do acids react with bases to form?

Answer 2

Salt and water in a neutralisation reaction.

Question 3

What do acids react with reactive metals to form?

Answer 3

A salt and a hydrogen gas.

Question 4

What do acids react with carbonate to form?

Answer 4

A salt, water, and carbon dioxide gas.

Question 5

What metals are unreactive metals? (do not react with acids)

Answer 5

Cu, Ag, Au

Question 6

When do acids display their properties?

Answer 6

Only when dissolved in water.

Question 7

Are all compounds that contain hydrogen acidic?

Answer 7

No. Only molecular compounds that ionise to form hydrogen ions are acidic.

Question 8

What does the strength of an acid refer to?

Answer 8

The extent of ionisation. (to form hydrogen ions)

Question 9

What does the concentration of acid refer to?

Answer 9

The amount of it per unit volume.

Question 10

What are the three types of basicity’s of acids?

Answer 10

Monobasic, Dibasic, Tribasic

Question 11

How do you test for hydrogen gas?

Answer 11

Place a burning splint at the mouth of the test tube. Hydrogen gas extinguishes the burning splint with a “pop” sound.

Question 12

How do you test for carbon dioxide gas?

Question 13

Name one example of a monobasic acid and a dibasic acid.

Answer 13

Monobasic – Hydrochloric acid (HCl)
Dibasic – Sulfuric acid (H2SO4)

Question 14

Explain why 0.100mol/dm^3 sulfuric acid has a higher concentration of H+ ions than 0.100mol/dm^3 hydrochloric acid.

Answer 14

Sulfuric acid has a higher concentration of H+ ions. Both acids have the same concentration and strengths. However, they have different basicity. Sulfuric acid is dibasic, so it produces 0.200mol/dm^3 of hydrogen ions. Hydrochloric acid is a monobasic acid, so it will produce only 0.100mol/dm^3 of hydrogen ions.

Question 15

What do bases form when reacted with ammonium salts?

Answer 15

Salt, water, and ammonium salts.

Question 16

What 2 substances do bases contain?

Answer 16

Oxide ions (O2-)
hydroxide ions (OH-) – produced by alkali

Question 17

How do you test for ammonia gas?

Answer 17

Ammonia turns a damp red litmus paper blue.

Question 18

What bases are insoluble?

Answer 18

Copper (II) oxide (CuO), and Iron (III) oxide (Fe2O3)

Question 19

What are soluble bases also known as?

Answer 19

Alkali

Question 20

What are the 4 physical properties of alkali?

Answer 20

1. Turns red litmus paper blue
2. Is an electrolyte
3. Feels slippery and soapy
4. Tastes bitter

Question 21

Give an example of a strong alkali and a weak alkali.

Answer 21

Sodium hydroxide (strong), Aqueous ammonia (weak)

Question 22

What pH range does a strong alkali have and what is its level of dissociation?

Answer 22

pH range of 10-14 and dissociates completely

Question 23

What pH range does a weak alkali have and what is its level of dissociation?

Answer 23

pH range of 7-10 and dissociates partially

Question 24

What colour is methyl orange in an acidic solution and alkaline solution?

Answer 24

Red in acidic solution and Yellow in alkaline solution.

Question 25

Which indicators change colour at the 3-5 pH range?

Answer 25

Methyl orange and screened methyl orange.

Question 26

What colour is Litmus in acidic solution in alkaline solution?

Answer 26

Red in acidic solution and Blue in alkaline solution.

Question 27

What pH range does litmus change colour at?

Answer 27

pH 5-8

Question 28

What colour is Thymolphthalein in acidic and alkaline solutions and what pH range does it change colour in?

Answer 28

Colourless in acidic solution and blue in alkaline solution.

Question 29

What colour is Bromothymol blue in acidic solution and alkaline solution?

Answer 29

Yellow/pink in acidic solution green endpoint in alkaline solution.

Question 30

What colour does a strong acid and weak acid turn Green Universal Indicator?

Answer 30

Strong acid --> Turns red Weak acid --> Turns yellow/orange

Question 31

What is the equation to calculate pH?

Answer 31

pH = -lg [H+]

Question 32

How do you calculate [H+] ions given the pH?

Answer 32

[H+] = 10^whatever the pH is

Question 33

What does the equivalence point refer to in titration?

Answer 33

The volume of reactants.

Question 34

What is the purpose of "liming" soil, and what is slaked lime made of?

Answer 34

Increases the pH level of the soil, reducing its acidity. Slaked line is calcium hydroxide.

Question 35

What are the main elements of fertiliser?

Answer 35

Ammonia and Nitrogen.

Question 36

What kind of oxides are most metal oxides?

Answer 36

Basic oxides.

Question 37

What are the properties of basic oxides?

Answer 37

Display basic properties, and are solid at room temperature.

Question 38

What metal oxides are not basic?

Answer 38

Zinc oxide, Aluminium oxide, Lead oxide.

Question 39

What kind of oxides are most non-metals?

Answer 39

Acidic oxides.

Question 40

What are the 4 types of oxides?

Answer 40

1. Basic 2. Acidic 3. Amphoteric 4. Neutral

Question 41

Name 3 neutral oxides?

Answer 41

H2O, CO, NO

Question 42

How would you determine how to prepare a salt, and how should you prepare it based on these conditions?

Answer 42

Solubility of salt in water, and solubility of the starting materials in water. Insoluble --> prepared by precipitation Soluble --> prepared by reactions of acid

Question 43

What salts cannot be prepared using the RAWIS method?

Answer 43

SPA: Sodium, Potassium, Ammonium