Acids and Bases Flashcards

1
Q

Define an acid

A

Proton Donor

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2
Q

Define a base

A

Proton Acceptor

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3
Q

Define a strong Acid

A

An acid (proton donor) which fully dissociates

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4
Q

Define a weak Acid

A

An acid ( proton donor) which only partially dissociates

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5
Q

Define pH

A

pH = -Log10[H+]

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6
Q

[H+] =

A

[H+] = 10-pH

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7
Q

Ionic Product of Water (Kw) =

A

Kw = [H+][OH-]

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8
Q

When calculating the pH of a strong acid use:

A

pH = -Log10[H+]

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9
Q

When calculating the pH of a strong base use:

A

Rearrange Kw = [H+][OH-] to get [OH-] then use pH = -Log10[H+]

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10
Q

When calculating the pH of a weak acid use:

A

Ka = [H+]2/[HA] and rearrange to get [H+]
then use pH = -Log10[H+]

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11
Q

When calculating the pH of a buffer use:

A

Ka = [H+][A-]/ [HA] and rearrange to get [H+] then use pH = -Log10[H+]

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12
Q

Chemical equation for Hydrochloric Acid + Sodium

A

HCl(aq) + Na(s) –> NaCl(aq) + ½ H2(g)

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13
Q

Chemical equation for Nitric Acid + Potassium Oxide

A

2HNO3 (aq) + K2O(s) –> 2KNO3 (aq) + H2O(l)

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14
Q

Chemical equation for Phosphoric Acid + Sodium Hydroxide

A

H3PO4(aq) + 3NaOH(s) –> Na3PO4(aq (aq) + 3H2O(l)

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15
Q

Chemical equation for Hydrochloric Acid + Calcium Oxide

A

2HCl (aq) + CuO(s) –> CuCl2 (aq) + H2O(l)

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16
Q

Chemical equation for Sulfuric Acid + Sodium Carbonate

A

H2SO4(aq) + Na2CO3(s) –> Na2SO4(aq) + CO2(g) + H2O(l)

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17
Q

Na2O(s) + H2O(l) –> products and pH

A

2Na+(aq) + 2-OH(aq) pH 13-14

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18
Q

MgO(s) + H2O(l) –> products and pH

A

Mg(OH)2(aq) pH 9-10

19
Q

P4O10(s) + 6H2O(l) –> products and pH

A

4H3PO4(aq) pH 0-1

20
Q

SO2(g) + H2O(l) –> products and pH

A

H2SO3(aq) pH 2-3

21
Q

SO3(g) + H2O(l) –> products and pH

A

H2SO4(aq) pH 0-1

22
Q

A difference of 1 on the pH scale means

A

a 10x difference in [H+]

23
Q

pKa =

A

-Log10Ka

24
Q

Ka =

A

10-pKa

25
Q

The value of Kw will alter with temperature, explain why pure water is always neutral

A

because [H+] = [-OH] at all times.

26
Q

Define a buffer

A

A BUFFER is a solution which can resist changes in pH when a small amount of acid or base is added

27
Q

What is an acid buffer made of

A

An ACIDIC BUFFER is made of a weak acid and a soluble salt of that acid. It maintains a pH below 7.

28
Q

What is a basic buffer made of

A

A BASIC BUFFER is made of a weak BASE and a soluble salt of that BASE. It maintains a pH above 7.

29
Q

Steps to get to pH in a buffer calculation when given concentration of weak acid CH3COOH, concentration of the salt CH3COONa and Ka value for weak acid.

A

sub values straight into Ka = [H+][ CH3COO]/[CH3COOH].
Rearrange to get [H+]
Use pH = -Log10[H+]

30
Q

Steps to get to pH in a buffer calculation when given volume and conc of both the weak acid and a base, where the weak acid is in excess, Ka value also given

A

Complete ICE box
Find new moles of acid and the moles of the salt produced.
sub mole* values into Ka = [H+][CH3COO]/[CH3COOH]. *volumes would cancel out so moles can be used instead of conc
Rearrange to get [H+]
Use pH = -Log10[H+]

31
Q

Steps to get to pH in a buffer calculation when enough base has been added to neutralise exactly half of the acid present.

A

Recognise this is a special situation - half neutralisation point so Ka = [H+]
Use pH = -Log10[H+]

32
Q

Formula for sulphuric acid

A

H2SO4

33
Q

Formula for nitric acid

A

HNO3

34
Q

Formula for phosphoric acid

A

H3PO4

35
Q

Formula for ethanoic acid

A

CH3COOH

36
Q

Formula for aluminium phosphate

A

AlPO4

37
Q

Formula for sodium ethanoate

A

CH3COONa

38
Q

Formula for lead (II) nitrate

A

Pb(NO3)2

39
Q

Formula for potassium sulphate

A

K2SO4

40
Q

Formula for magnesium chloride

A

MgCl2

41
Q

Explain how to chose a suitable indicator for a titration

A

A SUITABLE INDIATOR CHANGES COLOUR SOMEWHERE ON THE VERTICAL SECTION OF A pH TITRATION CURVE

42
Q

Define half neutralisation point

A

‘The point at which enough base has been added to neutralise exactly half of the acid’

43
Q

What does the vertical section of a titration curve show?

A

This indicates what the average titre would be which can be used in a calculation. The midpoint of this vertical section is the equivalence point.