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Chemistry module 6 > MOD6-INQ1 > Flashcards

MOD6-INQ1 Flashcards

1
Q

What colour does acid change litmus paper to

A

It’s turns blue litmus red

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2
Q

Why does H+ ions join with H30+ ions so quickly in reactions

A

A H+ ion is a bare proton with the charge of +1 making it extremely concentrated so in water it would combine with a water molecule to form a more stable molecule - H3O+

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3
Q

A base that dissolves in water is also known as

A

Alkalis

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4
Q

Which group base is all soluble

A

Group 1

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5
Q

Acid strength

A

The extent of ionisation or dissociation in water

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6
Q

Name 5 common strong acids

A

HCl, HBr, HI, H2SO4, HNO3

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7
Q

Name 4 strong bases

A

NaOH, KOH, Ca(OH)2, Ba(OH)2

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8
Q

Which group bases are strong but poorly soluble

A

Group 2

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9
Q

Many bases are _____ in ionic compounds

A

Anions

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10
Q

Because weak bases are anions in ionic compounds what must you do before showing it reacting with water

A

Dissociate the weak base

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11
Q

How is acid strength and concentration different

A

Acid strength refers to the extent of ionisation while acid concentration is the amount of acid in a given volume

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12
Q

What is generally the number which we consider as a concentrated acid

A

10M

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13
Q

What does Ka represent

A

Ka represent the position of the equilibrium for the dissociation of an acid in water

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14
Q

When talking about Ka reactions, is it dynamic or static reactions

A

Dynamic - never goes to completion

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15
Q

The stronger the acid = [Ka question]

A

The stronger the acid the more the equilibrium will lie on the right (product side) and the Ka will increase

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16
Q

Ka is only dependent on what factor

A

Temperature

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17
Q

Which Ka is higher 4.6x10^-5 or 4.6^-8

A

4.6^10-5

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18
Q

As the base strength increases= [Kb question]

A

Equilibrium will lie on the right due to the increase in concentration of products and Kb value will increase

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19
Q

Name a natural and synthetic indicators

A

Litmus paper comes from lichens and phenolphthalein from synthetic chemicals

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20
Q

Most indicators are made from what

A

Weak acids or base

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21
Q

In what state do indicators exist in

A

Dynamic equilibrium - incomplete reaction

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22
Q

What colour is methyl orange at low pH

A

Red

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23
Q

What colour is methyl orange is at a high pH

A

Yellow

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24
Q

What is the pH range is methyl orange

A

3.1-4.4

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25
What colour is methyl red is at low pH
Red
26
What colour is methyl red at a high pH
Yellow
27
What is the pH of colour change range of methyl red
4.8-6.0
28
What colour does litmus turn into at low pH
Red
29
What colour does litmus turn to at high pH
Blue
30
What is the pH of colour change range for litmus
4.5-8.3
31
What colour is bromothymol blue at low pH
Yellow
32
What colour is bromothymol blue at high pH
Blue
33
What is the pH of colour change range of bromothymol blue
6.0-7.6
34
What colour is phenol red at low pH
Yellow
35
What colour is phenol red at high pH
Red
36
What is the pH of colour change range of phenol red
6.8-8.4
37
What colour is phenolphthalein at low pH
Colourless
38
What colour is phenolphthalein at high pH
Pink
39
What is the pH of colour change range for phenolphthalein
8.2-10.0
40
When an acid reacts with ammonia what does it not produce that other reactions produce
Water
41
Why does ammonia not produce water in reactions
It does not contain oxygen in its formula
42
What is enthalpy of neutralisation
The amount of energy released or absorbed per mole of water formed
43
Neutralisation between a strong acid and strong base is what type of reaction
Exothermic
44
Weak acids and bases are what type of reactions
Less exothermic potentially even endothermic
45
Why are weak acid and base less exothermic than strong acid and bases
Because it is not completely dissociated in water the weak acid have to dissociate to release H+ ions to react with the OH- ions - dissociation is slightly endothermic
46
What is calorimetry
Procedure used to measure amount of heat transferred to (or from) a substance
47
What is Lavoisier idea of acids and base
Acids must contain oxygen
48
What is Davy idea of acids and bases
HCl does not have oxygen but is an acid - hydrogen is the main bitch not oxygen in acids
49
What is Liebig idea of acid and base
Proposed acids contained hydrogen which could be replaced by a reactive metal [expanded definition
50
What was Arrhenius idea of acids and bases
Acids and bases in aqueous solutions are electrolytes (conduct electricity) - acids ionise to produce H+ ions - bases ionise to produce OH- ions
51
Name a limitation of Arrhenius definition
It does not explain the basic behaviour of ammonia which doesn’t produce OH- ions in a reaction
52
What is Brønsted-Lowry idea of acids and base
An acid is a proton downer A base is a proton acceptor
53
What does Brønsted-Lowry definition do that Arrenhius can’t
It explains the basic behaviour of ionic compound solutions
54
Amphiprotic substance
A molecule or ion that is capable of both donating and accepting protons
55
Name 5 amphiprotic substances
HCO3-, HSO4-, H2PO4-, H2O+ , NH3
56
In labs what is commonly used for acids spills
Sodium hydrogen carbonate
57
Why is sodium hydrogen carbonate used for acids spills
It is weak, amphiprotic and produce carbon dioxide during neutralisation - safe to handle - does not increase the volume of liquid [its a solid]
58
Amphiprotic substances are a subset of what
Amphoteric substance
59
What are amphoteric substances
They can react with both acids and bases
60
Name a limitation of Brønsted-Lowry definition
IT cannot explain the acidic behaviours of some things that do not contain hydrogen [mainly non-metal oxides - CO2, So2, So3]
61
Two species in conjugate pairs differ by what
Differ by a proton (H+)
62
A strong acid will have
An extremely weak conjugate base
63
A weak acids will have a
Relatively strong conjugate base
64
Strong bases are what groups hydroxides
Group 1 and 2
65
What are 2 advantages of a pH meter over an indicator
It is more precise It does not alter the composition of solution like indicators do
66
What are 2 disadvantages of pH meter over an indicator
It requires calibration It’s cost is very high
67
Foods are generally _____ Cleaning products are generally ____
Acidic Basic
68
Aside from pH what else can a pH meter determine
Strength of acids and bases
69
Why are calculations for weak acids and base more complex
Equilibrium shifts after dilution (becoming more ionised)
70
Two strong acid solution or Two strong base solution = [related to moles]
Total moles of H+ or OH- will be the sum of ions from original solutions
71
What is a buffer solution
It resists changes in pH when small amounts of acid or base are added
72
What are buffers commonly made of
Weak acid and its conjugate base Or Weak base and its conjugate acid
73
What is the effectiveness of a buffer called
Buffer capacity
74
What does buffer capacity depend on
The total concentration of weak acid and conjugate base (vice versa) And The pH of buffer solution
75
Buffer capacity increases when
There are higher concentration of the weak acid and its conjugate base [more of each is available to buffer the addition of H3O+ and OH-]
76
When is a buffer most effective
When the pH is within 1 unit of its pKa
77
A buffer is most effect when what
The amounts of weak acid and conjugate base present are similar
78
What are 3 examples of a natural system where buffers play a major role
Our blood, in cells, large bodies of water (lakes)
79
Aliquot
Accurately known volume of liquid [usually the one transferred via pipette to the conical flask]
80
Analyte
A substance being analysed in titration [usually the one with unknown concentration - the one putting us through all this shit to find a number yeah its her]
81
Equivalence point
The point in neutralisation where the amounts of reactants are just sufficient to consume both reactants without excess of either [stoichiometric ratio is equal]
82
Titrand
The solution to which another solution (titrant) is added to during titration [usually in the conical flask]
83
Titrant
The solution that is being added into something else [usually in the burette]
84
Titre
The volume of the titrant used [in the burette]
85
Standard solution
A solution of precisely known composition and concentration
86
When is a primary standard produced
When a known mass of a substance of known high purity is dissolves to make A KNOWN VOLUME OF SOLUTION
87
What are features a primary standard solution should have
- high purity - unaffected by air exposure - non-hygroscopic {she don’t absorb water from air} - large molecular mass —> reduce percentage errors - be a solid - cheap + accessible - high water solubility (to be able to dissolve)
88
Name 3 common primary standard solutions
Sodium carbonate Potassium hydrogen phthalate Benzoic acid
89
Why is NaOH not a good primary standard
It’s hygroscopic—> absorbs water from air and the mass will then change
90
When is a secondary standard produced
When its concentration is determined via stoichiometry
91
The process of producing a secondary standard is called
Standardisation
92
Strong acid + metal carbonate (weak base) produce what type of salt
A natural salt (BUT solution is still acidic)
93
In pure water what is the [ ] of H+ and OH-
In pure water at 25C the pH=7 hence [H3O+] = [OH-] = 1.0x 10^-7M
94
What is Kw
Ionisation constant of water
95
If pH of a solution increases by 3, what happens to [ ] of H+ ions
Decreases by 1000 fold
96
If a pH solution increases by 3, what happens to the [ ] of OH ions
It increases by 1000 fold
97
What does ammonia dissociate into
Ammonium and hydroxide ion
98
What determines the pH of a buffer solution
The pKa of the acid and the relative concentration of the acids and its conjugate base

Chemistry module 6 (1 decks)

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