1.12 Acids and Bases Flashcards

1
Q

What is a bronsted lowry acid and base

A

A bronsted-lowry acid is a proton donor eg NH4+
A bronsted-lowry base is a proton acceptor eg OH-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define strong acid

A

An acid that completely dissociates to ions when in solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define weak acid

A

An acid that only slightly dissociates when in solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Equation for pH

A

pH= -log10[H+]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Equation for conc of H+

A

[H+]=10^-pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Equation for Kw and the constant value of it at 25C

A

Kw = [H+][OH-]
1x10^-14

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Kw

A

The equilibrium constant when water slightly dissociates to ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Equations involving Ka

A

Ka = 10^-pKa
pKa= -log10Ka
Ka=[H+][A-] / [HA]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What to use when HA is in excess

A

[HA] [A-] and Ka to find H+ then pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What to use when A- is in excess

A

Use Kw to find[H+] then pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What to use when HA=A-

A

Find pKa as pKa=pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When does neutralisation occur for
1. Strong acid strong base
2. Strong acid weak base
3. Weak acid strong base
4. Weak acid weak base

A
  1. pH 7
  2. < pH7 (more acidic)
  3. > pH7 (more basic)
  4. normally pH 7 but hard to determine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When is methylorange used and what colour does it turn when

A

More acidic neutralisation point
Red in acids and turns yellow at neutralisation point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When is phenolphthalein used and what colour does it turn when

A

More basic neutralisation point
Pink in alkalis and colourless at neutralisation point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a buffer solution

A

A solution which is able to resist changes in pH when small volumes of acid or base are added

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do buffer solutions contain

A

Either a weak acid or a weak base and the salt of the weak acid/base

17
Q

How to work out pH for acid and base

A

Find moles of each species
Calc conc when at equilibrium using total volume
Use Ka to find [H+] and pH

18
Q

How to work out pH for acid and salt

A

Find moles of salt
Use Ka to find pH

19
Q

Why are buffers used

A

To keep systems regulated
Important as enzymes or reactions in living organisms often require a specific pH which can be maintained using a buffer solution

20
Q

Equation for ionisation of water

A

H2O(l) <–> H+(aq) + OH-(aq)

21
Q

Give examples of strong acids

A

HCl
H2SO4
H3PO4

22
Q

Examples of strong bases

A

NaOH
CaCO3
Na2CO3

23
Q

Examples of weak acids

A

CH3COOH

24
Q

Examples of weak bases

A

NH3

25
Q

Properties of a good indicator

A

Sharp colour change
Distinct colour change so its obvious when endpoint reached