Theories of Acids and Bases

Question 1

Arrhenius acid

Answer 1

Substance which gives out H⁺ in water

Question 2

Arrhenius base

Answer 2

Substance which gives out OH^- in water

Question 3

Bronsted-Lowry acid

Answer 3

proton donor

Question 4

Bronsted-Lowry base

Answer 4

proton acceptor

Question 5

Conjugate Acid of H₃PO₄

Answer 5

H₂PO₄^-

Question 6

Conjugate acid of CH₃NH₂

Answer 6

CH₃NH₃⁺

Question 7

Conjugate base of H₂O

Answer 7

OH^-

Question 8

Conjugate acid of H₂O

Answer 8

H₃O⁺

Question 9

Strong acid

Answer 9

Acid which fully dissociates in water to give H⁺

Question 10

Strong base

Answer 10

Base which fully dissociates in water to give OH^-

Question 11

Weak acid

Answer 11

Acid which dissociates partially in water to give H⁺

Question 12

Weak base

Answer 12

Base which dissociates partially in water to give OH^-

Question 13

Degree of dissociation of acid

Answer 13

degree of dissociation = [H⁺] / initial [HA]

Question 14

pH

Answer 14

pH = - log₁₀[H⁺]

Question 15

pOH

Answer 15

pOH = - log₁₀[OH^-]

Question 16

Acid dissociation constant, K_a

Answer 16

K_a = [H⁺][A^-] / [HA]

Question 17

Base dissociation constant, K_b

Answer 17

K_b = [BH⁺][OH^-] / [B]

Question 18

pK_a

Answer 18

pK_a = - log₁₀K_a

Question 19

pK_b

Answer 19

pK_b = - log₁₀K_b

Question 20

Ionic product of water, K_w

Answer 20

K_w = [H⁺][OH^-]

Question 21

End point

Answer 21

The point at which the indicator changes colour in a titration.

Question 22

Equivalence point

Answer 22

The point at which the amount of H⁺ and the amount of OH^- in the titration is equal.

Question 23

Indicator suitable for weak acid - strong base titration

Answer 23

phenolphthalein
or
thymolphthalein

Question 24

Indicator suitable for strong acid - weak base titration

Answer 24

methyl orange
or
screened methyl orange

Question 25

pH at equivalence point of strong acid - strong base titration

Answer 25

7

Question 26

pH at equivalence point of weak acid - strong base titration

Answer 26

> 7

Question 27

pH at equivalence point of strong acid - weak base titration

Answer 27

< 7

Question 28

Equation to show pH of titration between HCl and NH₃ is < 7

Answer 28

NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺

Question 29

Equation to show pH of titration between CH₃COOH and NaOH is > 7

Answer 29

CH₃COO^- + H₂O ⇌ CH₃COOH + OH^-

Question 30

Buffer solution

Answer 30

A solution which can resist pH changes when small amounts of acid or base are added.

Question 31

Acidic buffer is made of

Answer 31

a weak acid and its conjugate base
or
a weak acid and its salt

Question 32

Equation to show action of buffer when small amount of acid is added to CH₃COOH / CH₃COO^-Na⁺ buffer system

Answer 32

CH₃COO^- + H⁺ → CH₃COOH

Question 32

Alkaline (or basic) buffer is made of

Answer 32

a weak base and its conjugate acid
or
a weak base and its salt

Question 33

Equation to show action of buffer when small amount of base is added to CH₃COOH / CH₃COO^-Na⁺ buffer system

Answer 33

CH₃COOH + OH^- → CH₃COO^- + H₂O

Question 34

Equation to show action of buffer when small amount of acid is added to NH₃ / NH₄Cl buffer system

Answer 34

NH₃ + H⁺ → NH₄⁺

Question 35

Equation to show action of buffer when small amount of base is added to NH₃ / NH₄Cl buffer system

Answer 35

NH₄⁺ + OH^- → NH₃ + H₂O

Question 36

Equation for blood buffer system

Answer 36

H₂CO₃ + H₂O ⇌ HCO₃^- + H₃O⁺

Question 37

Equations to show how blood buffer system removes excess acid

Answer 37

H₃O⁺ + HCO₃^- → H₂CO₃ + H₂O
followed by
H₂CO₃ ⇌ CO₂ + H₂O

Question 38

Equations to show how blood buffer system removes excess base

Answer 38

H₂CO₃ + OH^- → HCO₃^- + H₂O

Question 39

At 25^oC, pH + pOH has a value of

Answer 39

14