Acids, Bases, and Salts

Question 1

define acid

Answer 1

a compound which when dissolved in water yields hydronium ions as the only positively charged ions

Question 2

define bases

Answer 2

a base is a compound which reacts with hydronium ions of an acid to give salt and water only

Question 3

define alkali

Answer 3

a compound which when dissolved in water yields hydroxyl ions as the only negatively charged ions

Question 4

classification of acids based on source

Answer 4

1. organic: derived from plants (oxalic, tartatic, citric)
2. inorganic: derived from minerals (HCl, H2SO4)

Question 5

classification of acids on basis of molecular composition

Answer 5

1. hydracids: contain hydrogen and a non metal other than oxygen
2. oxyacids (acids containing hydrogen, another element, and oxygen)

Question 6

define basicity of acids

Answer 6

the number of hydrogen ions which can be produced per molecule of acids in aqueous solution or the number of hydroxyl ions with which one molecule of an acid combines

Question 7

why is acetic acid CH3COOH monobasic

Answer 7

it has four hydrogen atoms in it but ionises in aqueous solution to produce one hydrogen ion per molecule of the acid

Question 8

define acidity of bases

Answer 8

number of hydroxyl ions which can be produced per molecule of the base in aqueous solution or the number of hydrogen ions with which a molecule of a base combines

Question 9

types of salts formed by tribasic acids

Answer 9

2 acidic, 1 normal

Question 10

Arrhenius theory

Answer 10

acids are substances which dissociate in aqueous solution to give H+ ions. Strong acids dissociate almost completely, while weak acids dissociate partially

Question 11

Lowry-Bronsted’s theory

Answer 11

acids are proton donors, bases are proton acceptors

Question 12

define neutralization

Answer 12

the process due to which H+ ions of an acid react completely or combine with OH- ions of base to give salt and water only

Question 13

define heat of neutralization

Answer 13

the amount of heat liberated when 1 gram equivalent of an acid or a base is completely neutralised

Question 14

define indicators

Answer 14

weak organic compounds which change colour in accordance with the pH of the solution
dissociate slightly in solution producing ions and undissociated molecules. colour of ions depends on hydrogen ion concentration or pH of medium

Question 15

when is conc. of H+ and OH- ions equal

Answer 15

at 10^-7 mol/dm^3 (25 C)

Question 16

product of two ionic concentrations

Answer 16

10^-14 (at 25C)

Question 17

define pH

Answer 17

the negative logarithm (to the base 10) of the hydrogen ion concentration expressed in moles/litre

Question 18

define salt

Answer 18

a compound formed by partial or complete replacement of the replaceable (ionizable) hydrogen ion of an acid, by a metallic ion or ammonium ion

Question 19

define acid salt

Answer 19

the salts formed by partial replacement of the replaceable hydrogen ion of an acid molecule by a basic radical

Question 20

define normal salt

Answer 20

the salts formed by complete replacement of the replaceable hydrogen ion of an acid molecule by a basic radical

Question 21

define basic salt

Answer 21

formed by partial replacement of hydroxyl radicals of a diacidic or triacidic base with an acid radical

Question 22

general methods of preparation of salts

Answer 22

1. direct combination
2. displacement
3. double decomposition
4. neutralization of an insoluble base
5. neutralization of an alkali (titration)
6. action of dil. acid on carbonates/ bicarbonates

Question 23

how to prepare insoluble salt from another insoluble salt

Answer 23

convert the insoluble salt reactant to soluble salt using dil. HNO3
then do double displacement and combine it with another soluble salt

Question 24

why can’t H2SO4 be directly added to PbCO3 (insoluble) to make PbSO4

Answer 24

because PbSO4 is insoluble and forms a coating on PbCO3 , thereby the reaction slowly comes to a stop

Question 25

define hydrolysis of salts

Answer 25

reaction in which salts react with water to form base (alkali) and an acid i.e. a solution which is acidic, alkaline, in nature