Acids and Bases

Question 1

What is an acid?

Answer 1

A substance that dissolve in water to produce hydrogen ions

Question 2

What are some common acids?

Answer 2

Ethanoic acid, CH3COOH
Hydrochloride acid, HCL
Nitric acid, HNO3
Sulfuric acid, H2SO4

Question 3

What are the properties of acids?

Answer 3

1. Sour taste
2. Dissolve in water to form solutions which conduct electricity
3. Turn blue litmus paper red
4. React with reactive metals to form a salt and hydrogen gas
5. React with carbonate and hydrogen carbonate to form a salt, water and carbon dioxide
6. React with metal oxide and hydroxide to form a salt and water only
7. pH value less than 7
8. Turn universal indicator orange or red

Question 4

What is a base?

Answer 4

A substance that reacts with an acid to produce salt and water only

Question 5

What are some common bases?

Answer 5

1. Sodium oxide, Na2O
2. Zinc oxide, ZnO
3. Copper(ii) oxide, CuO
4. Magnesium oxide, MgO
5. Magnesium hydroxide, Mg(OH)2
6. Aluminium hydroxide, Al(OH)2

Question 6

What is the general equation of bases?

Answer 6

base + acid —> salt + water

Question 7

What is the use of acids?

Answer 7

1. Make fertilisers
2. Make detergents
3. Used as a battery in cars

Question 8

What is the use of a base?

Answer 8

1. Used in medicine

Question 9

What is an alkali?

Answer 9

Alkalis are soluble bases, that dissolve in water to produce hydroxide ions

Question 10

What are common alkalis?

Answer 10

1. Sodium hydroxide, NaOH
2. Potassium hydroxide, KOH
3. Calcium hydroxide, Ca(OH)2
4. Barium hydroxide, Ba(OH)2
5. Aqueous ammonia, NH3(aq)

Question 11

What are the uses of alkalis?

Answer 11

1. Make soaps

2. Used in agriculture

Question 12

What are the properties of alkalis?

Answer 12

1. Bitter taste and feel soapy
2. Turn red litmus paper blue
3. React with acids to form a salt and water only
4. React with ammonia salts to form a salt, water and ammonia gas
5. pH value more than 7
6. Conduct electricity
7. Turn universal indicator blue or violet

Question 13

What is neutralisation reaction?

Answer 13

The hydrogen ions, H+, from the acid and the hydroxide ions, OH-, from the alkali react to form water

Question 14

What is pH scale?

Answer 14

A set of numbers from 0 to 14 which is used to indicate whether a substance is acidic, neutral or alkaline

Question 15

What is the pH of common substances?

Answer 15

About..
1 battery acid
2 lemon juice 
3 vinegar
5 orange juice 
7 blood
8 sea water
11 ammonia
13 bleach
14 lye

Question 16

What to use to measure the pH of a given solution?

Answer 16

Indicator
pH sensor attached to a data logger
pH meter

Question 17

What are the pH values of the type of soils?

Answer 17

1. Peat, 4.0
2. Clay, 6.0
3. Loam, 6.5
4. Sand, 7.0

Question 18

What are the pH range of the types of plants?

Answer 18

1. potatoes, peanuts, 5.5-6.5
2. wheat, plum, 6.5-7.5
3. barley, cabbages, 7.5-8.5

Question 19

When does most plants grow best?

Answer 19

Most plants grow best when the soil is neutral or slightly acidic

Question 20

What is the reason why pH of soil is unsuitable for the plant growth?

Answer 20

1. Too much fertiliser added to the soil

2. Environmental pollution such as acidic rain

Question 21

What is liming?

Answer 21

The addition of bases such as calcium oxide and calcium hydroxide to reduce the acidicity of solids

Question 22

Strong acid

Answer 22

A strong acid is an acid that dissociate fully in water to produce hydrogen ions

Question 23

Weak acid

Answer 23

A weak acid is an acid that dissociate partially in water to produce hydrogen ions

Question 24

Steps for precipitation

Answer 24

1. Add reagent A and reagant B together in a beaker
2. Filter the mixture to obtain the residue, ____
3. Wash the residue with distilled water
4. Dry the residue between sheets of filter paper