Acids + Alkalis + Salts (4) Flashcards
1
Q
The pH scale goes from ___ up to ___
A
0 - 14
2
Q
The strongest acid has a pH of ___
A
0
3
Q
The strongest alkali has a pH of ___
A
14
4
Q
A neutral substance has a pH of ___
A
7
5
Q
Example of a neutral substance
A
Pure water
6
Q
Colour change of universal indicator:
A
Universal will turn many different colours to give a specific pH
7
Q
Colour change of litmus paper:
A
Neutral: Purple
Acidic: Red
Alkaline: Blue
8
Q
Colour change of phenolphthalein:
A
Acidic: Colourless
Alkaline: Pink
9
Q
Colour change of methyl orange:
A
Acidic: Red
Alkali: Yellow
10
Q
What is a base
A
A substance that can neutralise an acid
11
Q
What is the difference between an alkali and a base
A
Alkalis are bases which are soluble in water
12
Q
What is the name of the reaction between an acid and a base
A
Neutralisation
13
Q
Acid + base → …
A
→ salt + water
14
Q
(H+) + (OH-) → _______
A
H20
15
Q
Metal oxides are generally _________
A
Bases
16
Q
If the acid is hydrochloric acid then the salt will be a …
A
Metal chloride
17
Q
|f the acid is sulfuric then the salt will be a …
A
Metal sulfate
18
Q
If the acid is nitric then the salt will be a …
A
Metal nitrate
19
Q
Salts can be either soluble or ___________
A
Insoluble
20
Q
Which 3 elements are always soluble
A
Sodium, potassium and ammonium
21
Q
Most chlorides, most sulfates and all nitrates are ___________
A
Soluble
22
Q
All nitrates are ____________
A
Soluble
23
Q
Most chlorides are soluble except for ___________ ____________
A
Silver chloride
24
Q
Most sulfates are soluble except for ___________ sulfates and _____________ sulfates
A
Barium sulfates
Calcium sulfates
25
Most carbonates are _____________ - except for ___________, _____________ and ______________ carbonates (these are the 3 elements that are always soluble)
Insoluble
Sodium
Potassium
Ammonium
26
Titrations are used to find out the ___________ of an acid or alkali
Concentrations
27
Titrations are used to find out exactly how much acid is needed to ________________ a quantity of alkali
Neutralise
28
How to do a titration
1) Add about 25cm3 of alkali to a conical flask and 2-3 drops of indicator
2) Fill a burette with acid and use it to add acid to the alkali a bit at a time - while swirling the flask
3) The indicator will change colour when it is neutralised
4) Record the volume of acid used to neutralise the alkali and repeat to make the result more reliable.
29
Titrations:
1) Add about _______ of alkali to a conical flask and 2-3 drops of indicator
2) Fill a ___________ with acid and use it to add acid to the alkali a bit at a time - while swirling the flask
3) The indicator will change colour when it is ______________
4) Record the volume of acid used to neutralise the alkali and repeat to make your result more ___________.
25cm3
Burette
Neutralised
Reliable
30
What does soluble mean
If a substance is soluble then it's capable of being dissolved especially in water
31
What does insoluble mean
If a substance is insoluble then it is incapable of being dissolved
32
What is a solute
The minor component in a solution, dissolved by the solvent
33
What is a solvent
The liquid in which a solute is dissolved to form a solution
34
What is a solution
The solution is the mixture formed when a solute has dissolved in a solvent
35
What ways are there of making a soluble salt
Using acids and insoluble bases
| Using an alkali
36
How to make a soluble salt using acids and insoluble bases
Add the insoluble base to the acid, the solid will dissolve in the acid as it reacts.
You know when all the acid has been neutralised because the excess solid will sink to the bottom and remain there.
You can then filter out the excess base to get the salt solution.
To get pure, solid crystals of the salt - evaporate off the water.
37
How to make a soluble salt using an alkali
Alkalis are soluble bases so you can't filter them out.
So you don't know when it has neutralised.
Therefore you must use an indicator to show when the reaction has finished.
The best way of doing this is a titration.
Then repeat without an indicator so the salt isn't contaminated
38
What is the difference between an alkali and a base
An alkali is a soluble base
| A base is insoluble
39
How do you make an insoluble salt
Precipitation reactions
40
How to make an insoluble salt using a precipitation reaction.
Just pick 2 solutions that contain the ions you need. E.g for barium sulfate (insoluble). You just need a solution that contains barium ions and a solution that contains sulfate ions. You literally just mix 2 solutions containing the ions that you need
41
Acid + metal →
→ Salt + Hydrogen
42
Acid + metal oxide →
→ Salt + Water
43
Acid + metal hydroxide →
→ Salt + Water
44
Acid + Carbonate →
→ Salt + Water + Carbon Dioxide
45
Sulphuric acid formula
H2SO4
46
Hydrochloric acid formula
HCI
47
Nitric acid formua
HNO3
48
H2SO4 =
HCI =
HNO3 =
```
H2SO4 = Sulphuric acid
HCI = Hydrochloric acid
HNO3 = Nitric acid
```
49
What makes an acid acidic
They all form H+ ions when dissolved in water
50
All acids are ____________ so you need _______ protection and gloves
Corrosive
| Eye
51
When Hydrogen chloride dissolves in water, it splits into ___ and ____ ions
H+(aq)
| Cl-(aq)
52
HCI(__) ----(water)----> H+(__) + Cl- (__)
HCI(g) ----(water)----> H+(aq) + Cl- (aq)
53
Are bases soluble or insoluble
Insoluble (a soluble base is an alkali)
54
Alkalis are ____________ so you need eye protection and _________
Corrosive
| Gloves
55
Sodium hydroxide formula
NaOH
56
Potassium hydroxide formula
KOH
57
Calcium hydroxide formula
Ca(OH)2
58
NaOH =
KOH =
Ca(OH)2 =
```
NaOH = Sodium hydroxide
KOH = Potassium hydroxide
Ca(OH)2 = Calcium hydroxide
```
59
What makes an alkali alkaline?
All alkalis form hydroxide ions, OH-(aq) when disolved in water, making the solution alkaline
60
NaOH(__) --> ----(water)----> Na+(__) + OH-(__)
NaOH(s) --> ----(water)----> Na+(aq) + OH-(aq)
61
Acids produce ____(aq) ions and
| Alkalis produce _____(aq) ions
Acids produce H+(aq) ions and
| Alkalis produce OH-(aq) ions
62
What happens when acids and alkalis react
They neutralise each other
63
H+(__) + OH-(__) -----> ____(__)
H+(aq) + OH-(aq) ------> H2O(l)
64
_________, a neutral substance with a pH of ___ is formed when acidic ____ ions and alkaline ____ ions react with each other. This is what happens in a ___________ experiment
```
Water
7
H+
OH-
Titration
```
65
```
Universal indicator
pH 0-2 =
pH 2-4 =
pH 5 =
pH 6 =
pH 7 =
pH 8-9 =
pH 10-14 =
```
```
pH 0-2 = Strong red
pH 2-4 = Weaker red
pH 5 = Orange
pH 6 = Yellow
pH 7 = Green
pH 8-9 = Blue
pH 10-14 = Purple
```
66
A salt is made when the __________ ions in an acid are replace by _______ ions
Hydrogen
| Metal
67
The names of salts have 2 parts. The first name is the name of the _______ and the second name is the name of the ________ it was made from
Metal
| Salt
68
Metal chlorides are made from...
Hydrochloric acid
69
Metal sulphates are made from ...
Sulphuric acid
70
Metal nitrates are made from ...
Nitric acid
71
Metal(__) + Acid(__) --> Salt(__) + Hydrogen(__)
Metal(s) + Acid(aq) --> Salt(aq) + Hydrogen(g)
72
Metal(s) + Acid(aq) --> Salt(aq) + Hydrogen(g) works for reactive metals but is ___________ if the metal is too reactive (e.g ___ or ___) because the reaction is ___________
Dangerous
Na or K
Exothermic
73
How to do Metal(s) + Acid(aq) --> Salt(aq) + Hydrogen(g) experiment
1. Add metal to acid until no more bubbling is seen
2. Filter to remove the unreacted metal leaving salt solution
3. Heat the solution in evaporating dish to remove some of the water, then allow to cool to form crystals
4. Filter to remove the crystals and dry them (warm oven or leave for all water to evaporate)
74
When doing a Metal(s) + Acid(aq) --> Salt(aq) + Hydrogen(g) experiment. First you: 1. Add metal to acid until no more bubbling is seen. What does this mean?
All the acid has reacted
75
When doing a Metal(s) + Acid(aq) --> Salt(aq) + Hydrogen(g) experiment. The second thing you do is filter to remove what?
What does this leave behind?
Unreacted metal
| Salt solution
76
When doing a Metal(s) + Acid(aq) --> Salt(aq) + Hydrogen(g) experiment. The 3rd thing you do is heat the solution in an evaporating dish to remove what? Then you allow it to _____ to form what?
Some of the water
| Cool to form Crystals
77
When doing a Metal(s) + Acid(aq) --> Salt(aq) + Hydrogen(g) experiment. The final thing you do is filter to remove the _________ and dry them in a warm place which allows what?
Crystals
| Water to evaporate
78
If we want to make salts containing the ions of unreactive metals then rather than using the metal we can react the solid with what?
An insoluble metal oxide
79
To make salts by metal oxide + acid ---> salt + water... what is the method
1. Add metal oxide to acid until no more will dissolve (all acid has reacted), while warming the acid
2. Some of the metal oxide won't disappear since all the acid has reacted - so we filter it to remove this unreacted metal oxide - leaving the salt solution
3. Heat the solution in an evaporating dish to remove some of the water, then allow to cool to form crystals
4. Filter to remove the crystals and dry them (warm oven) leave them for water to evaporate
80
Why do we not see any bubbling in metal oxide(s) + acid(aq) --> Salt(aq) + water(l)
There is no hydrogen
81
Metal oxide + acid ---> salt + water but we only want the ______ so we ___________ the crystals to remove the unwanted ________
Salt
Evaporate
Water
82
Insoluble metal carbonates react with acids in a very similar way to metal _________ and can be used in the same way, to make salts of ____________ metals, the only difference is that _________ __________ is formed as well as the other products meaning that we would see __________ as well at the metal carbonate ______________ as it reacts
```
Oxides
Unreactive
Carbon dioxide
Fizzing
Disappearing
```
83
To make salts by metal cabonate(s) + acid(aq) ---> salt(aq) + water(l) + carbon dioxide(g)... what is the method
1. Add metal carbonate to acid until no more fizzing occurs (all the acid has reacted)
2. Filter to remove the unreacted metal carbonate
3. Heat the solution in an evaporating dish to remove some of the water, allow to cool to form crystals
4. Filter to remove the crystals and dry them (warm oven or leave for all water to evaporate)
84
Metal hydroxide (__) + Acid(__) --> Salt(__) + Water(__)
Metal hydroxide (aq) + Acid(aq) --> Salt(aq) + Water(l)
85
Metal Oxide + Acid --> Salt + Water works for:
All metal oxides. Useful for making salts of unreactive metals.
86
Metal Carbonate + Acid --> Salt + Water + Carbon Dioxide works for:
All insoluble metal carbonates. Useful for making salts of unreactive metals
87
Metal hydroxide + Acid --> Salt + Water works for:
All alkalis. Useful for reactive metals, and to make ammonium salts
88
To make salts by Metal Hydroxide + Acid --> Salt + Water, what is the method...
1. Add acid progressively to the alkali or soluble metal carbonate, testing the pH
2. Stop when the pH = 7
3. Heat the solution in an evaporating dish to remove some of the water, then allow to cool to form crystals
4. Filter to remove the crystals and dry them or leave in a warm place for all water to evaporate
89
_________ is a molecule, NH3
| Whereas ___________ is an ion NH4+
Ammonia
| Ammonium
90
What is formed when ammonia dissolves in water
Ammonium hydroxide
91
Ammonium nitrate and ammonium sulphate are important fertilisers because they are rich in ___________
Nitrogen
92
What is a precipitate
A solid formed in a solution when a product of a reaction is insoluble
