Topic 6- Acids And Alkalis Flashcards
(94 cards)
1
Q
How can aqueous solutions be categorised?
A
Acidic
Alkaline
Neutral
2
Q
Why are the hazard symbols important?
A
The show what precautions we should take and how to handle them
3
Q
What is the following hazard symbol?
A ball exploding
A
Explosive
4
Q
What is the following hazard symbol?
A star in a human chest
A
Health hazard
5
Q
What is the following hazard symbol?
Liquid poured on a surface and hand that is steaming
A
Corrosive
6
Q
What is the following hazard symbol?
A flame
A
Flammable
7
Q
What is the following hazard symbol?
A dead fish, barren tree
A
Harmful to the environment
8
Q
What is the following hazard symbol?
An O/ball on fire
A
Oxidising
9
Q
What is the following hazard symbol?
Skull and cross bones
A
Toxic
10
Q
What is the following hazard symbol?
Exclamation mark
A
Hazardous
11
Q
What is the following hazard symbol?
Looks like a cricket bat
A
Gas under pressure
12
Q
What do acids all have present?
A
Hydrogen
13
Q
What makes the solution acidic?
A
When dissolved in water the hydrogen ions are released and they dissociate
It’s the H+ ion that makes the solution acidic
14
Q
What are 3 examples of acids?
A
- Hydrochloride acid
- Sulfuric acid
- Nitric acid
15
Q
What is the chemical formula for hydrochloric acid?
A
HCl
16
Q
What is the chemical formula for sulfuric acid?
A
H2SO4
17
Q
What is the chemical formula for nitric acid?
A
HNO3
18
Q
What do all alkalis contain?
A
The hydroxide ion
19
Q
What makes the solution alkaline?
A
When the alkalis dissolve in start the hydroxide ions are released and dissociate. It is the OH- that makes the solution alkaline.
20
Q
What is the chemical formula for potassium hydroxide?
A
KOH
21
Q
What is the chemical formula for calcium hydroxide?
A
Ca(OH)2
22
Q
What is the chemical formula for sodium hydroxide?
A
NaOH
23
Q
What are 3 examples of alkalis?
A
- Potassium hydroxide
- Calcium hydroxide
- Sodium hydroxide
24
Q
What do we use the pH scale for?
A
To measure acidity and alkalinity (0-14)
25
Why do substances change colour?
Depending on the pH
26
What is pH related to?
The concentration of hydrogen ions
27
The lower the pH…
The higher the concentration of hydrogen ions
28
Increasing pH means…
Concentration of hydrogen ions is increasing
29
What colour is universal indicator in a strong acid?
Red
30
What colour is universal indicator in a weak acid?
Orange
31
What colour is universal indicator in a neutral solution?
Green
32
What colour is universal indicator in a weak alkali?
Blue/ dark green
33
What colour is universal indicator in a strong alkali?
Purple
34
What colour is litmus in an acid?
Red
35
What colour is methyl orange in an acid?
Red
36
What colour is litmus in a neutral, weak alkali and strong alkali?
Blue
37
What colour is menthol orange in a neutral solution?
Orange
38
What colour is methyl orange in an alkali?
Yellow
39
What colour is phenolphthalein in an acid and neutral solution?
Colourless
40
What colour is phenolphthalein in an alkali?
Pink/magenta
41
Why is an acid strong?
It fully dissociates in solution releasing all hydrogen ions
42
Why is an acid weak?
It only partially dissociates in solution releasing fewer hydrogen ions is
43
What is concentration?
The number of particles compared to water, resulting in concentrated or dilute solutions
44
What is pH affected by?
Strong or weak
Concentrated or dilute
45
What is neutralisation?
A chemical reaction where an acid and a base cancel each other out to produce a solution of pH 7. A salt and water is produced
46
What does neutralisation produce?
A salt and water
47
What is the general word equation for neutralisation?
Acid + alkali —> salt + water
Acid + base —> salt + water
48
What are bases?
A substance which neutralises acids
49
What are alkalis in relation to bases?
Alkalis are soluble bases
All alkalis are bases but not all bases are alkalis
50
If a substance neutral uses acid but does not dissolve in water, it’s called a …
Base
51
How do you name a salt?
The first part is the meta, from the base. The second part comes from the acid
52
If the acid is hydrochloric, what is the salt ending?
Chloride
53
If the acid is nitric, what is the salt ending?
Nitrate
54
If the acid is sulfuric, what is the salt ending?
Sulfate
55
If the acid is phosphoric, what is the salt ending?
Phosphate
56
How do you prepare a soluble salt?
Heated sulfuric acid in waterbath at 5O °c
Added copper oxide power in and mixed til in excess
Heat again tomake sure re action has occured. filtered solution to obtain excess copper sultate solution
put inevaporating dish over beakerof waterand heat using a bunsen burner
whenwater is half evaporated. allow to cool fora few days then pay dry .
57
If the H+ concentration is increases by a factor of 10…
The pH decreases by 1
58
Why do we need to balance equations?
Because atoms cannot be created or destroyed so they must be must be balanced
59
What is the word equation for a reaction of an acid and a metal?
Acid + Metal —> Salt + Hydrogen
60
How do you test for hydrogen?
Put a lit splint in the gas
The squeaky pop sound produced indicates the presence of hydrogen
61
What metals in the reactivity series will react with acids?
Any above hydrogen
62
Why won’t any metals below hydrogen react with acids?
Not reactive enough to displace H+ from acid
63
What is the word equation for the reaction of an acid and metal carbonate?
Acid + metal —> salt + water + carbon dioxide
64
In this reaction, describe what happens to the products:
Hydrochloric acid + copper carbonate —> copper chloride + water + carbon dioxide
Carbon dioxide bubbles
Copper chloride is a blue solution
Copper carbonate is a green powder
Lime water goes cloudy with carbon dioxide
65
What is a precipitate?
A solid suspended in solution
66
What happens when 2 soluble salts react?
Form an insoluble and soluble salt that then need to be filtered
67
What common substances are soluble in water?
All common sodium, potassium and ammonium compounds
All nitrates
Most chlorides
Most surfaces
Sodium carbonate, potassium carbonate, ammonium carbonate
Sodium hydroxide, potassium hydroxide, ammonium hydroxide
68
What common substances are insoluble in water?
Silver and lead chloride
Lead, barium and calcium sulfate
Most carbonates
Most hydroxides
69
If the concentration of hydrogen ions increases by a factor of 10,
The pH decreases by 1
70
If the concentration of hydrogen ions is decreased by a factor of 10,
The pH increases by 1
71
What does pH relate to?
Hydrogen ions in a solution
72
What are the 2 methods to produce soluble salts?
1. Reacting an acid with a base
2. Acid + alkali reaction: Titration
73
What is titration?
Reacting an acid with an alkali
74
What is the method for titration, reacting an acid with an alkali?
1. Fill burette with an acid to meniscus point
2. Using a glass pipette and pipette filler, measure out set volume of alkali
3. Transfer alkali to conical flask and place flak on white tile (to observe later colour change)
4. Add phenophthalein to alkali (a couple of drops)
5. Add acid to alkali and swirl it constantly to ensure even distribution
6. Once end point if reached and colour change is observed, record volume of acid needed to neutralise alkali
7. Measure out the same volume of acid and alkali, mix them together. (No indicator needed)
8. Crystallisation process
75
What is the method for titration, reacting an acid with an alkali?
1. Fill burette with an acid to meniscus point
2. Using a glass pipette and pipette filler, measure out set volume of alkali
3. Transfer alkali to conical flask and place flak on white tile (to observe later colour change)
4. Add phenophthalein to alkali (a couple of drops)
5. Add acid to alkali and swirl it constantly to ensure even distribution
6. Once end point if reached and colour change is observed, record volume of acid needed to neutralise alkali
7. Measure out the same volume of acid and alkali, mix them together. (No indicator needed)
8. Crystallisation process
76
How does neutralisation work in terms of ions?
At the start the beaked only contains acid, so pH is low due to number of H+ ions
As sodium hydroxide is added the -OH ions from alkali react with H+ ions
H+ + -OH —> H2O
This removed the H+ ions from the solution increasing the pH until 7
If more alkali is added the pH will go above 7
77
What happens to pH when you add an acid to an alkali?
It decreases
78
A reaction between an acid and a base is called…
Neutralisation
79
What is the formula for hydrochloric acid?
HCl
80
Sodium hydroxide + hydrochloride acid —> + water
Sodium chloride
81
Which has is always produced when a metal is added to an acid?
Hydrogen
82
In alkaline solution, red litmus turns…
Blue
83
When sulphuric acid reacts with zinc the products are …
Zinc surface and hydrogen
84
What gas pops a lighted splint?
Hydrogen
85
What ions do all acids form when dissolved in water?
H+
86
Sodium carbonate + hydrochloric acid —>
Sodium chloride + water + carbon dioxide
87
A soluble base is
Alkali
88
Alkalis in solution are sources of
Hydroxide ions
89
Phenolphthalein turns
Colourless in acid and pink in alkali
90
Correct sequence for making copper sulphate
Put some sulphuric acid into a beaker. Add excess copper oxide. Warm and stir. Filter off unreacted copper oxide.
Concentrate filtrate. Cool to crystallise copper sulphate.
Put some sulphuric acid into a beaker. Warm and stir. Add excess
91
What is a strong acid?
An acid that fully dissociate in water to from H+ ions
92
What colour is litmus in alkali?
Blue
93
What is a weak acid?
An acid that partially dissociate in water to form H+ ions
94
What salt is produced when magnesium hydroxide reacts with sulphuric acid?
Magnesium sulfate
