Strong And Weak Acids

Question 1

what do acids do in aqueous solutions

Answer 1

they ionise meaning they produce hydrogen ions (H+)

Question 2

what is H+

Answer 2

a hydrogen ion with just a proton and nothing else, its lost its one electron

Question 3

what does an acid have to do in order to be a strong acid

Answer 3

• completely ionise in water

- all acid particles dissociate to release H+ ions

Question 4

what does an acid have to do in order to be a weak acid

Answer 4

• not fully ionise in a solution

- small proportion of acid particles dissociate to release H+ ions

Question 5

what type of reaction is the ionisation of a weak acid

Answer 5

a reversible reaction

Question 6

what does the ionisation of a weak acid do

Answer 6

sets up an equilibrium between the undissociated and dissociated acid

Question 7

since only a few acid particles release H+ ions during the ionisation of a weak acid, what does it result in in terms of the created of the equilibrium

Answer 7

the position of the equilibrium lies well to the left

Question 8

why are strong acids more reactive than weak acids of the same concentration

Answer 8

• reactions of acids involve H+ ions reacting with other substances
• higher concentration of H+ ions results in an increased rate of reaction
• strong acid’s H+ ions completely ionise, so rate of reaction is higher
• meaning they are more reactive then weak acids

Question 9

what is pH

Answer 9

the measure of the concentration of H+ ions in a solution

Question 10

how is the pH scale related to the concentration of H+ ions numerically

Answer 10

for every decrease of 1 on the pH scale, the concentration of H+ ions increases by a factor of 10 (and vice versa)

Question 11

what is the difference in concentration between an acid with a pH of 4 to one with a pH of 5`

Answer 11

acid with pH 4 has 10 times the concentration of H+ ions than the acid with pH 5

Question 12

what is the formula for calculating H+ concentration change with pH change

Answer 12

• factor H+ ion concentration changes by = 10^-x
• x is the difference in pH
• if pH falls from 7 to 4 the difference is -3
• so in the formula it is written as 10^-(-3) = 10^3
• that is 10 with 3 0s, so 1,000 higher concentration of H+

Question 13

what does the formula for calculating H+ concentration change with pH change mean in terms of the difference between strong and weak acids with the same concentration

Answer 13

the pH of a strong acid is always less than the pH of a weaker acid of they have the same concentration