acids & bases

Question 1

brønsted–lowry acid

Answer 1

proton donor

Question 2

brønsted–lowry base

Answer 2

proton acceptor

Question 3

conjugate acid–base pair

Answer 3

two species that differ by one proton

Question 4

relative strength relationship of conjugate acid-base pairs

Answer 4

stronger the acid, weaker the conjugate base (if an acid readily donates a proton, its conjugate base does not readily accept it back)

stronger the base, weaker the conjugate acid (if a base readily accepts a proton, its conjugate acid does not readily donate it back)

Question 5

amphiprotic substance

Answer 5

behaves as a brønsted–lowry acid & base

able to donate & accept protons

(e.g. H₂O)

Question 6

Ka trend

Answer 6

larger Ka = greater extent of dissociation = stronger acid

smaller Ka = lower extent of dissociation = weaker acid

Question 7

extent of dissociation trend

(Ka)

Answer 7

greatest for the first dissociation & smaller for each subsequent dissociation

(each acid in the series becomes progressively weaker)

it becomes harder to lose a proton as the acid species becomes more negative

Question 8

strong acid & base

Answer 8

ionizes completely in aqueous solution

readily donates/accepts protons

high conductivity (more ions)

“→”

Question 9

strong acids

Answer 9

HCl

HNO₃

H₂SO₄

Question 10

strong bases

Answer 10

NaOH

Ba(OH)₂

(group I hydroxides in general)

Question 11

weak acid & base

Answer 11

ionizes partially in aqueous solution

high proportion of undissociated particles

low conductivity (less ions)

“⇌”

Question 12

weak acids

Answer 12

CH₃COOH

H₂CO₃

(carboxylic acids in general)

Question 13

weak bases

Answer 13

NH₃

(amines in general)

Question 14

strength vs concentration

Answer 14

strength refers to the degree of dissociation

concentration refers to the relative amount of solute in a given volume of solution

Question 15

water characteristics

Answer 15

weak electrolyte

self-ionizes to a very small extent

Question 16

buffer

Answer 16

solutions that are conjugate in nature & resists changes in pH when small amounts of acid or base are added

until the buffer is exhausted (broken), causing pH change

Question 17

indicator characteristics

Answer 17

weak acid (HIn) or weak base (BOH)

conjugate acid-base pair (color A & color B)

Question 18

when does an indicator change colour ?

Answer 18

pKa = pH or Ka = [H⁺]

Question 19

explain the relationship between the pH range of an indicator & its pKa

Answer 19

pH range : HIn (color A) & In⁻ (color B)

pH = pKa : indicator changes color (Hln = In⁻)

pH < pKa : indicator is color A (HIn > In⁻)

pH > pKa : indicator is color B (HIn < In⁻)

Question 20

pKa trend

Answer 20

high pKa = low Ka = weak acid

low pKa = high Ka = strong acid

Question 21

equivalence point

Answer 21

moles of reactants are equal

chemical reaction finishes

Question 22

end point

Answer 22

indicator changes colour

additional drop of titrant causes sharp change in colour