Acids and Bases (Chem)

Question 1

What is an acid?

Answer 1

An acid is a substance, a proton donor, that produces hydrogen ions when dissolved in water

Question 2

Hydrochloric acid formula:

Answer 2

HCL

Question 3

Nitric acid formula:

Answer 3

HNO3

Question 4

Sulfuric acid formula

Answer 4

H2SO4

Question 5

Ethanoic acid formula

Answer 5

CH3COOH

Question 6

Properties of acids:

Answer 6

• sour taste
• conduct electricity (due to the mobile ions produced when dissolved in water)
• turn blue litmus paper red

Question 7

acid + metal –>

Answer 7

salt + hydrogen

Question 8

acid + base –>

Answer 8

Salt + water

Question 9

acid + carbonate –>

Answer 9

salt + water + carbon dioxide

Question 10

Difference between strong/weak acids

Answer 10

• strong acids ionise completely in aqueous solutions
• weak acids ionise partially in aqueous solutions

Question 11

What does it mean by “strength of acid”

Answer 11

refers to the extent of ionisation of the acid in aqueous solution.
(The smaller the extent of ionisation, the weaker the acid)

Question 12

What is an alkali?

Answer 12

It is a soluble base that produces hydroxide ions when dissolved in water

Question 13

Properties of alkalis:

Answer 13

• bitter taste
• feel soapy
• conduct electricity (due to the mobile ions produced when they dissolve in water)
• turn red litmus paper blue

Question 14

alkali + acid –>

Answer 14

salt + water

Question 15

what is the reaction between alkali and acid called?

Answer 15

Neutralisation

Question 16

alkali + ammonium salt –>

Answer 16

salt + water + ammonia

Question 17

What does it mean by acidity?

Answer 17

Acidity depends on the concentration of hydrogen ions relative to that of hydroxide ions in a solution

Question 18

What does it mean by alkalinity?

Answer 18

Alkalinity depends on the concentration of hydroxide ions relative to that of hydrogen ions in a solution

Question 19

What is the purpose of PH scale?

Answer 19

It is used to indicate the acidity and alkalinity of solutions

Question 20

What does a universal indicator do?

Answer 20

It shows a variety of colours at different PH values

Question 21

What is the colour of Methyl orange indicator when soaked in acid/alkaline?

Answer 21

acidic - red
alkaline - yellow

Question 22

What is the colour of screened Methyl orange indicator when soaked in acid/alkaline?

Answer 22

acidic - violet
alkaline - green

Question 23

What is the colour of bromothymol blue indicator when soaked in acid/alkaline?

Answer 23

acidic - yellow
alkaline - blue

Question 24

Describe the importance of controlling PH of soil

Answer 24

Soil of appropriate pH provides sufficient amounts of the required nutrients to plants. (usually suitable between ph 5-7)

Question 25

Explain why soil becomes more acidic overtime

Answer 25

due to different environment conditions, such as acid rain

Question 26

State what can be added to soil when it becomes too acidic

Answer 26

Bases, such as calcium hydroxide, can be added to soil that is too acidic.

Question 27

Explain the process of liming and how it could controlled

Answer 27

During liming, the base reacts with the acids present in the soil to raise the pH of the soil. To ensure that the right amount of base is added to soil, the pH of soil should be measured before and during the process of liming

Question 28

What is precipitation and how does it work?

Answer 28

It is a method of preparing an insoluble salt in water. It is the reaction between one reactant containing the cation of the salt and another reactant containing the anion of the salt - soluble salt + soluble salt --> insoluble salt - acid + soluble salt --> insoluble salt Method steps: 1 Mix soluble salt and the other soluble salt in the beaker 2 filter to collect the precipitate of the desired insoluble salt as3 residue 4 Wash the precipitate with cold distilled water to remove impurities 5 Dry the precipitate between a few sheets of filter paper

Question 29

What is titration and how does it work?

Answer 29

It is a method of preparing soluble salt in water It is the reaction between an acid + (alkali or soluble carbonate) or anything that contains (grp 1 metal or ammonium)