physical chemistry; acids & bases

Question 1

what are brønsted-lowry acids?

Answer 1

they are proton donors

Question 2

what occurs when acids are mixed with water?

Answer 2

H ions are released

Question 3

what ions make solutions acidic?

Answer 3

H⁺ ions don’t exist on their own in water, they form H₃O⁺ ions & these ions make the solution acidic

Question 4

write the generic equation for acids + water

Answer 4

HA (aq) + H₂O (l) → H₃O⁺ (aq) + A⁻ (aq)

HA: represents an acid

Question 5

write the generic equation for bases + water

Answer 5

B (aq) + H₂O (l) → BH⁺ (aq) + OH⁻ (aq)

B: represents a base

Question 6

what occurs when bases are mixed with water?

Answer 6

as the base reacts with H⁺, OH⁻ ions are formed

Question 7

weak acid

Answer 7

backwards reaction favoured so not many H⁺ ions are produced

Question 8

give an example of weak acids & its equation

Answer 8

CH₃COOH (ethanoic acid) & other carboxylic acid
CH₃COOH ⇌ CH₃COOH + H⁺

Question 9

strong acid

Answer 9

forwards reactions favoured strongly so lots of H⁺ ions are produced

Question 10

give examples of strong acids & its equation

Answer 10

HCl, H₂SO₄ & HNO₃
HCl ⇌ HCl⁻ + Cl⁻

Question 11

strong base

Answer 11

forward reaction favoured strongly so many OH⁻ ions are produced

Question 12

gives examples of strong bases & its equation

Answer 12

NaOH & KOH
NaOH ⇌ Na⁺ + OH⁻

Question 13

weak base

Answer 13

backwards reaction favoured so not many OH⁻ ions are produced

Question 14

give an example of a weak base & its equation

Answer 14

NH₃
NH₃ + H₂O ⇌ NH₄⁺ + OH⁻

Question 15

when acids & bases react with water, what type of reaction is formed?

Answer 15

a reversible reaction

Question 16

state how well a strong/weak base would dissociate

Answer 16

strong base: dissociates (ionise) almost completely
weak base: dissociates poorly

Question 17

state how well a strong/weak acid would dissociate

Answer 17

strong acid: dissociates almost completely
strong base: dissociates poorly

Question 18

state what happens to the protons when acids & bases react with one another

Answer 18

protons are exchanged

Question 19

write the generic equation for an acid donating a proton to a base

Answer 19

HA (aq) + B ⇌ BH⁺ (aq) + A⁻ (aq)