Acids, Bases, and Buffers Flashcards

1
Q

Acids

A

Proton donors

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2
Q

Bases

A

Proton acceptors

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3
Q

Monotropic Acid

A

Can donate one mole of protons per mole of acid
e.g. HCl

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4
Q

Diprotic Acids

A

Can donate two moles of protons per mole of acid
e.g. H2SO4

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5
Q

Strong acids

A

Dissociate completely in water

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6
Q

Strong bases

A

Ionise completely in water
e.g. NaOH and KOH

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7
Q

Weak acids

A

Dissociate weakly in water

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8
Q

Weak bases

A

Ionise weakly in water

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9
Q

Water can act as either:

A

Acid- donates proton
Base- accepts proton

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10
Q

Water dissociates into:

A

Hydroxonium ions H3O+
Hydroxide ions OH-

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11
Q

Ionic product of water

A

Kw = [H+] [OH-]

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12
Q

Effect of increasing temperature on Kw

A

Kw increases
pH decreases
Equilibrium moves to the right

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13
Q

pH scale

A

Measure of H+ present in a solution

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14
Q

pH

A

-log[H+]

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15
Q

[H+]

A

10^-pH

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16
Q

Weak acids and Weak bases in aqueous solution

A

Dissociate slightly

17
Q

Concentration

A

Amount of acid in moles per cubic meter (mol dm-3)

18
Q

Strength of an Acid

A

Extent to which it ionises

19
Q

Acid dissociation constant

A

Ka = [H+] ^2 / [HA]

20
Q

pKa

A

pKa = - log(Ka)

21
Q

Ka

22
Q

Equivalence Point

A

Colour change when mixing two solutions in equal proportion (vertical line) neutralisation occurs here

23
Q

Methyl Orange

A

Red ——-> Yellow
Colour change: 3.1 - 4.4

24
Q

Phenolphthalein

A

Colourless —–> Pink
Colour change: 8.3 - 10

25
Indicator for Strong Acid / Strong Base
Methyl Orange Phenolphthalein
26
Indicator for Strong Acid / Weak Base
Methyl Orange
27
Indicator for Weak Acid / Strong Base
Phenolphthalein
28
Indicator for Weak Acid / Weak Base
None - no sharp pH change
29
Buffer
Chemical that resists change in pH when a small amount of acid or base is added
30
Acidic Buffer
Resists change in pH to keep the pH below pH 7, made from weak acid and its salt
31
Basic Buffer
Resists change in pH to keep the pH above pH 7, made from a weak base and its salt
32
Salt dissociation
Dissociate strongly
33
Uses of buffers
Shampoo Washing powder Blood
34
Why is H2O not shown in Kw = [H+][OH-]
Water is almost always constant
35
Why is pH probe washed with distilled water in between calibration measurements?
Different solutions must not contaminate eachother
36
Why do we add small amounts of solution (e.g. NaOH) between each measurement when we are measuring the pH?
To avoid missing the end point