5.1

Question 1

how do you calculate just normal rate

Answer 1

change in concentration/ time

Question 2

how do you work out the overall order of an equation?

Answer 2

the sum of all the individual orders

Question 3

how do you use half life to calculate rate constant?

Answer 3

k= ln2/half of time

Question 4

what’s a clock reaction?

Answer 4

Measuring time taken for a visual change to occur to calculate how concentration affects rate

Question 5

How do you determine k from a rate-concentration graph?

Answer 5

rate/ concentration

Question 6

What is the rate determining step?

Answer 6

slowest step in a multi-step reaction

Question 7

how does temp affect kp or kc?

Answer 7

If forward reaction is exothermic, an increase in temp would decrease k

If forward reaction is endothermic, an increase in temp would increase k

Question 8

how does conc. and pressure affect kp or kc?

Answer 8

It doesn’t. The equilibrium can act to counteract the changes.

Question 9

If k > 1

Answer 9

The equilibrium favours the right

Question 10

If k < 1

Answer 10

The equilibrium favours the left

Question 11

What’s a bronsted Lowry acid?

Answer 11

A proton donor

Question 12

what’s a bronsted Lowry base?

Answer 12

A proton acceptor

Question 13

Acid + alkali

Answer 13

-> salt + water

Question 14

Acid + carbonate

Answer 14

-> salt + carbon dioxide + water

Question 15

Acid + base

Answer 15

-> Salt + water

Question 16

Acid + metal

Answer 16

-> salt + hydrogen

Question 17

List all the strong acids you need to know for A level (6)

Answer 17

HCl (hydrochloric acid)
HNO3 (nitric acid)
H2SO4 (sulphuric acid)
HBr (hydrobromic acid)
HI (hydriodic acid)
HClO4 (chloric (VII) acid)

Question 18

What’s the acid dissociation constant?

Answer 18

measure of acid dissociation

Question 19

equation for Ka (strong acids)?

Answer 19

Ka= [H+] x [A-]/ [HA]

Question 20

how do you turn Ka to pKa and then back again

Answer 20

Ka -> pKa = -ln(Ka)

pKa -> Ka = 10^-pKa

Question 21

What does a high Ka suggest?

Answer 21

strong acid

Question 22

What does a high pKa suggest?

Answer 22

weak acid

Question 23

How do you calculate pH?

Answer 23

-log[H+]

Question 24

how do you calculate [H+] from pH?

Answer 24

10^-pH

Question 25

What can we assume when calculating pH of strong acids?

Answer 25

that [HA] = [H+] this is because H+ completely dissociates

Question 26

What can we assume when calculating pH of a weak acid?

Answer 26

that [H+] = [A-] as H+ and A- form at equal amounts due to weak acids only partially dissociating

Question 27

Ka for weak acids?

Answer 27

[H+]^2 / [HA]

Question 28

What are the limitations of the scientific estimations surrounding Ka?

Answer 28

It can be assumed that so little dissociation occurs in weak acids that initial[HA] ≃[HA]equilibrium If the sample is a stronger weak acid, this assumption is wrong

Question 29

How would you practically determine the Ka of a weak acid?

Answer 29

Using a pH probe and the known conc. of the acid

Question 30

What is the ionic product of water?

Answer 30

Kw = [H+][OH-]

Question 31

Is water an acid or base? What does this mean for equilibrium

Answer 31

It's both. Can act as an acid by donating a proton: H2O ⟶ H+ + OH- Can act as a base by acting as a proton acceptor: H2O ⟶ H3O+ Therefore it's a constant exchange of protons so it is in equilibrium: H2O ⥭ H+ + OH-

Question 32

How do you make a buffer? (Two ways)

Answer 32

1. A weak acid and its salt 2. Excess weak acid + strong alkali

Question 33

If you add acid to a buffer, which way will equilibrium shift?

Answer 33

Left

Question 34

If you add alkali to buffer, which way will equilibrium shift?

Answer 34

right

Question 35

how do you calculate pH of a buffer

Answer 35

[H+] = Ka x [HA]/ [A-]

Question 36

What's the buffer system of the blood?

Answer 36

H2CO3 -> H+ + HCO3-

Question 37

What is the ideal blood pH, what are the conditions if too high or low?

Answer 37

7.35 - 7.45 too high- acidosis too low- alkalosis

Question 38

what is the equivalence point of a titration?

Answer 38

The point at which the volume of one solution has reacted completely with the other and it matches the stoichiometry

Question 39

what is the end point of the titration?

Answer 39

Equal concentrations of the weak acid and conjugate base forms of the indicator

Question 40

What does the equivalence point look like on a graph?

Answer 40

The straight line

Question 41

How do you calibrate a pH probe?

Answer 41

Wash it in deionised water Blott it dry Dip it in a solution of known pH and check its reading it properly