Chemical Changes And Structure #4: Acids And Bases Flashcards

1
Q

Acids have a pH of…

A

Less than 7

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2
Q

Pure Water + Neutral Solutions have a pH…

A

of 7

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3
Q

Alkalis have a pH of…

A

Greater than 7

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4
Q

Why do chemists use electronic pH probes to accurately measure the pH of a solution?

A

Because using a colour chart is subjective

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5
Q

What do chemists use to accurately measure the pH of a solution?

A

pH probes

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6
Q

Examples of Acids

A
  • Vinegar
  • Lemonade
  • Soda Water
  • Coke
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7
Q

Examples of Alkalis

A
  • Baking Soda
  • Dishwasher Powder
  • Bleach
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8
Q

Acids are compounds that produce ____ when dissolved in water

A

H+ (aq) ions

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9
Q

Alkalis are compounds that produce ____ when dissolved in water

A

OH- (aq) ions

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10
Q

Formula of Hydrochloric Acid

A

HCl

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11
Q

Ions present in Hydrochloric acid (HCl)

A

H+ (aq) and Cl- (aq)

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12
Q

Formula for sulfuric acid

A

H2 SO4

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13
Q

Ions Present in Sulfuric Acid (H2SO4)

A

2H+ (aq) and SO4 2- (aq)

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14
Q

Formula for Nitric Acid

A

HNO3

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15
Q

Ions present in Nitric Acid (HNO3)

A

H+(aq) and NO3 - (aq)

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16
Q

Formula for sodium hydroxide

A

NaOH

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17
Q

Ions Present in Sodium Hydroxide (NaOH)

A

Na+ (aq) and OH- (aq)

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18
Q

Ions present in Potassium Hydroxide (KOH)

A

K+ (aq) and OH- (aq)

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19
Q

Formula of Potassium Hydroxide

A

KOH

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20
Q

Formula for Calcium Hydroxide

A

CaOH2

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21
Q

Ions present in Calcium Hydroxide (CaOH2)

A

Ca 2+ (aq) and 2OH-

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22
Q

How can you tell if something is an acid or alkali? ***

A
  • It has the word acid in its name if it’s an acid
  • It has the word hydroxide (OH-) in it if it’s an alkali
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23
Q

What is the concentration of H+ (aq) and OH- (aq) in neutral solutions?

A

It’s equal

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24
Q

Give an example of equal concentration in neutral solutions

A

H2O ⇌ H+ (aq) + OH- (aq)

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25
Q

What is a reversible reaction?

A

One which can proceed in both directions:

Reactant + Reactant ⇌ Product(s)

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26
Q

What is equilibrium? (2)

A
  • Equilibrium is when the rates of the forward and reverse reactions are equal
  • At equilibrium, the concentrations of reactants and products remain constant, although not necessarily equal
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27
Q

What happens to the concentrations of reactants and products at equilibrium?

A

They remain constant, although not necessarily equal

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28
Q

Equilibrium in water (5)

A

1 - Water molecules are constantly breaking up to form ions which in turn are constantly combining to reform water molecules

2 - This equilibrium exits in water and all aqueos solutions

3 - H20 ⇌ H+ (aq) + OH- (aq)

4 - Only 1 in 55million water molecules break up into ions

5 - Therefore, water is a poor conductor of electricity

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29
Q

What are water molecules constantly doing?

A

Breaking up to form ions which in turn are constantly combining to reform water molecules

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30
Q

What does the equilibrium of molecules breaking up to form ions and then combining to reform molecules exist in?

A

Water and all aqueos solutions

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31
Q

Why is water a poor conductor of electricity?

A

Only 1 in 55million water molecules break up into ions

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32
Q

What is pH a measure of?

A

The hydrogen ion concentration

p = potens (power)
H = Hydrogen (H+)

33
Q

Acidic solutions contain more ___ than ___

A

H+ (aq) ions , pure water

34
Q

Alkaline solutions contain more ___ than ___

A

OH- (aq) ions, pure water

35
Q

Neutral solutions contain ___ concentrations of ___

A

H+ (aq) and OH- (aq) ions

36
Q

What do concentrated acids and alkalis contain?

A

A lot of acid or alkali in a small volume of water

37
Q

What do dilute acids and alkalis contain?

A

A small amount of acid or alkali in a large volume of water

38
Q

The effects of dilution (adding water) to an acid?

A

It increases the pH of the solution as the concentration of H+ (aq) ions decreases

39
Q

The effects of dilution (adding water) to an alkali?

A

It decreases the pH of the solution as the concentration of OH- (aq) ions decreases

40
Q

What do non-metals burn in oxygen to produce?

A

Non-Metal Oxides.

C(s) + O2 (g) -> CO2 (g)

41
Q

What do non-metal oxides dissolve in water to form? Give an example.

A

Acidic Solutions.

CO2 (g) + H2O (l) -> H2CO3 (aq)

42
Q

What do metals burn in oxygen to produce? Give an example.

A

Metal oxides. (All of which are bases)

2Mg (s) + O2 (g) -> 2MgO (s)

43
Q

All metal oxides are…

A

Bases

44
Q

What happens if a metal oxide (metals burned in the presence of oxygen) is soluble in water? Give an example.

A

An alkali.

MgO (s) + H2O (l) -> Mg(OH)2 (aq)

45
Q

What do all soluble metal hydroxides do?

A

Dissolve in water to produce alkaline solutions

46
Q

What do insoluble oxides and hydroxides not do?

A

Affect the pH of water (because they don’t dissolve in it)

47
Q

What page is the solubility of compounds found?

A

8

48
Q

What is ammonia the common name for?

A

Nitrogen Hydride

49
Q

What does ammonia do (as a gas)? What does this make it?

A

Neutralise acids, making it a base

50
Q

What is ammonia (as a covalent molecule)?

A

It dissolves in water to produce an alkaline solution

51
Q

Formula of ammonia dissolving in water to produce an alkaline solution

A

NH3 (g) + H2O ⇌ NH4 + (aq) + OH - (aq)

52
Q

What is the formula of ammonium?

A

NH4

53
Q

What is the formula of ammonia?

A

NH3

54
Q

What is a neutralisation reaction?

A

The reaction of acids with bases

55
Q

What happens to the pH in a neutralisation reaction?

A

It moves toward 7

56
Q

What is a base? ***

A

Compounds which react with H+ (aq) ions to produce water
(A SOLUBLE ALKALI)

57
Q

Bases include:

A
  • Metal Oxides
  • Metal Hydroxides
  • Metal Carbonates
  • Ammonia (kind of an exception but still a base)
58
Q

What are the 4 main neutralisation reactions?

A

Acid + Metal hydroxide -> salt + water
Acid + Metal oxide -> salt + water
Acid + Metal carbonate -> salt + water + carbon dioxide
Acid + metal -> salt + hydrogen

59
Q

What are salts?

A

Ionic compounds that are formed during neutralisation

60
Q

What happens during neutralisation?

A

The hydrogen ions of the acid are replaced by metal ions or ammonium ions

61
Q

What do salts contain?

A
  • a positive metal ion (or ammonium ion) from the base
  • a negative ion from the acid
62
Q

How are salts named?

A
  • positive metal ion of the base (ammonia becomes ammonium)
  • negative ion present in the acid
    (hydrochloric acid makes chloride salts)
    (nitric acid makes nitrate salts)
    (sulphuric acid makes sulfate salts)
63
Q

What is the form for HCl (aq) + NaOH (aq) -> NaCl (aq) + H20

A

Acid + alkali -> salt + water

64
Q

What is a spectator in?

A

An ion which appears on both sides of the ionic equation. It is present in the reaction mixture but takes no part in the reaction.

65
Q

n =

A

CV

66
Q

n stands for

A

Number of moles

67
Q

C stands for

A

Concentration (l-1)

68
Q

V stands for

A

Volume (l)

69
Q

c =

A

n/v

70
Q

v =

A

n/c

71
Q

What is a standard solution?

A

One whose concentration is known accurately

72
Q

Why is knowing the exact concentration in a standard solution important?

A

If you are going to carry out calculations involving that equation

73
Q

Procedure of making standard solution

A
  1. Accurately weigh the substance in a small beaker
  2. Add a small volume of deionised water and stir to dissolve
  3. Transfer to a standard flask along with the washings from the beaker
  4. Make up to the mark carefully using distilled water
  5. Invert several times to mix thoroughly
74
Q

What is a volumetric titration?

A

An experiment in which the volumes of reacting liquids are accurately measured

75
Q

How is the alkali/acid measured in acid/alkali titrations?

A

Alkali = pipettes
Acid = bufete

76
Q

How can we calculate the concentration of an acid or alkali?

A

If the concentration of the alkali is known or vice versa

77
Q

Procedure of volumetric titration

A
  1. Pipette 25ml of alkali into the conical flask.
  2. Add universal indicator and swirl
  3. Fill the burette with acid, zero, and remove funnel

Then proceed to rough titration:
4. Add 1ml of acid at a time and swirl after each addition. Note the end-point volume

Proceed to Accurate Titration:
5. Add the acid until 1ml from the rough end point. Carefully add the acid drop-wise and swirl after each addition.
6. Continue titrating until you have 2 concordant results that agree within 0.2ml.

78
Q

Soluble metal oxides form

A

Alkalis

79
Q

Soluble non-metal oxides form

A

Acids