Acids And Bases

Question 1

Natural indicators

Answer 1

Litmus paper, red cabbage extract, turmeric.

Question 2

Synthetic indicators

Answer 2

Phenolphthalein, methyl orange.

Question 3

Olfactory indicators

Answer 3

Vanilla extract, clove and onion (lose their smell in basic medium)

Question 4

Red cabbage extract colour change

Answer 4

Red in acid and green in basic.

Question 5

Turmeric colour change

Answer 5

Yellow in acid and red in base

Question 6

Acids’ physical properties

Answer 6

• sour in taste

- turns blue litmus red

Question 7

Organic acids

Answer 7

Formic, acetic, malic, citric, tartaric

Question 8

Inorganic/Mineral acids

Answer 8

HCl, H2SO4, HNO3, HF, H2CO3, H2SO3

Question 9

What are concentrated and dilute acids?

Answer 9

Conc. Acids - Acids which contain more H+ ions per unit volume. Dil. Acids are the opposite.

Question 10

How to dilute acid/base?

Answer 10

By adding drop by drop solution to water with careful study. This is because adding water to solution is highly exothermic. This heat can only be absorbed by large volumes of water. Also, the thick viscous solution may break the surface tension and cause splash.

Question 11

Reaction of acid with metal

Answer 11

Hydrogen + Salt

Question 12

Reaction of acid with metal oxide

Answer 12

Water + Salt

Question 13

What is the nature of metal oxides?

Answer 13

Since metal oxides react with acids to give salt and water, they are basic in nature.

Question 14

Reaction of acid with metal carbonate and bicarbonate

Answer 14

Carbon dioxide + water + salt

Question 15

What happens when excess carbon dioxide is passed through line water?

Answer 15

Milkiness is lost because calcium bicarbonate is formed, which soluble in water.

Question 16

What is temporary hardness of water?

Answer 16

It is caused due to carbonates and bicarbonate of calcium. It can be removed by boiling.

Question 17

CaCO3 forms

Answer 17

Limestone, chalk and marble

Question 18

Reaction of acid with bases

Answer 18

‘Neutralisation’

Salt + water

Question 19

Properties of bases

Answer 19

• bitter in taste and soapy to touch
• turns red litmus blue
• water soluble bases are alkali
• metal oxides also act as bases
• conduct electricity in solution

Question 20

Reaction of bases with metals

Answer 20

Salt + H2 (but not all metals react with bases) (Only Zn, Sn and Al react)

Question 21

Reaction of bases with non-metal oxides

Answer 21

Salt + H2O

Question 22

Reaction of bases with acids

Answer 22

Salt + H2O

Question 23

How are acids stored?

Answer 23

They are never metal containers as they can corrode. They are stored in glass bottles.
But HF cannot be stored in glass as HF reacts with silica (it is stored in wax coated glass or plastic)

Question 24

What is basicity?

Answer 24

Number of replaceable H+ ions in an acid. Called so it indicates the number of bases it can neutralise.