C5 - Chemical Changes Flashcards
1
Q
What is an acid?
A
When dissolved in water, its solution has a pH value less than 7. Acids release H+ ions when added to water
2
Q
What is an alkali?
A
When dissolved in water, its solution has a pH value more than 7. Alkalis release OH- ions when added to water
3
Q
What is a base?
A
the oxide, hydroxide, or carbonate of a metal that will react with an acid and be neutralised, forming a salt + water
4
Q
What is a displacement reaction?
A
a reaction in which a more reactive element takes the place of a less reactive element in one of its compounds or in solution
5
Q
What is electrolysis?
A
the breakdown of a substance containing ions by electricity
6
Q
What is equilibrium?
A
the point in a reversible reaction at which the forward and backward rates of reaction are the same. Therefore, the amounts of substances present in the reacting mixture remain constant
7
Q
What is a half equation?
A
an equation that describes reduction (gain of electrons) or oxidation (loss of electrons)
8
Q
What is an ionic equation?
A
an equation that shows only those ions or atoms that change in a chemical reaction
9
Q
What is a metal ore?
A
a rock that contains enough of a metal or metal compound that it is worth extracting the metal
10
Q
What is neutral?
A
a solution with a pH value of 7 which is neither acidic nor alkaline.
11
Q
What is neutralisation?
A
the chemical reaction of an acid with a base in which a salt and water are formed. If the base is a carbonate or hydrogen carbonate, carbon dioxide is also produced in the reaction
12
Q
What is an ore?
A
a rock which contains enough metal to make it economically worthwhile to extract the metal
13
Q
What is oxidation/oxidised?
A
a reaction where oxygen is added to a substance / or when electrons are lost from a substance
14
Q
What is pH?
A
a number which shows how strongly acidic or alkaline a solution is
15
Q
What is the reactivity series?
A
a list of elements in order of their reactivity
16
Q
What is reduction / reduced?
A
a reaction in which oxygen is removed or electrons are gained
17
Q
What is a salt?
A
an ionic compound (can be formed when an acid reacts with a base)
18
Q
What are strong acids?
A
these acids completely ionise in aqueous solutions
19
Q
What are weak acids?
A
acids that do not dissosiate completely in aqueous solutions
20
Q
What are 3 strong acids?
A
- Hydrochloric Acid
- Sulfuric Acid
- Nitric Acid
21
Q
What is an example of a weak acid?
A
*Ethanoic Acid
22
Q
What is the formula of Hydrochloric Acid
A
HCl
23
Q
What is the formula of Sulfuric Acid
A
H₂SO₄
24
Q
What is the formula of Nitric Acid
A
HNO₃
25
What is the formula of Ethanoic Acid
CH₃COOH
26
What is the equation for Hydrochloric Acid ionising?
HCl -> H⁺ + Cl⁻
27
What is the equation for Sulfuric Acid ionising?
H₂SO₄ -> 2H⁺ + SO₄²⁻
28
What is the equation for Nitric Acid ionising?
HNO₃ -> H⁺ + NO₃⁻
29
What is the equation for Ethanoic Acid ionising?
CH₃COOH ⇌ H⁺ + CH₃COO
30
What is the equation for an acid reacting with a metal oxide?
acid + metal oxide → salt + water
31
What is the equation for an acid reacting with a metal hydroxide?
acid + metal hydroxide → salt + water
32
What is the equation for an acid reacting with a metal carbonate?
acid + carbonate → salt + water + carbon dioxide
33
What type of salt is produced with sulfuric acid?
sulfate
34
What type of salt is produced with nitric acid?
nitrate
35
What type of salt is produced with hydrochloric acid?
chloride
36
What would be the typical PH of a strong concentrated acid?
0 or 1
37
What would be the typical PH of a strong dilute acid?
2 or 3
38
What would be the typical PH of a weak concentrated acid?
4 or 5
39
What would be the typical PH of a weak dilute acid?
5 or 6
40
What would be the reaction with magnesium of a strong concentrated acid?
vigorous fizzing
41
What would be the reaction with magnesium of a strong dilute acid?
fizzing
42
What would be the reaction with magnesium of a weak concentrated acid?
gentle fizzing
43
What would be the reaction with magnesium of a weak dilute acid?
hardly any fizzing
44
What colour would the universal indicator be with a strong concentrated acid?
red
45
What colour would the universal indicator be with a strong dilute acid?
red
46
What colour would the universal indicator be with a weak concentrated acid?
orange
47
What colour would the universal indicator be with a weak dilute acid?
yellow
48
What proportion of molecules would react with water to for H⁺ with a strong concentrated acid?
all
49
What proportion of molecules would react with water to for H⁺ with a strong dilute acid?
all
50
What proportion of molecules would react with water to for H⁺ with a weak concentrated acid?
few
51
What proportion of molecules would react with water to for H⁺ with a weak dilute acid?
few
52
How do you identify an acid?
It will contain H⁺ in its formula (i.e. HCl or H₂SO₄)
53
How do you identify an alkali?
It will contain OH- in its formula (i.e. NaOH or KOH)
54
How do you identify a base?
It will contain oxide (O), carbonate (CO₃²⁻), or hydroxide (OH-) (i.e. MgO or PbCO₃)
55
How do you identify a salt?
It will be the product of an acid base reaction, (i.e. Potassium Nitrate or Zinc Chloride)
56
Can an acid be a base?
no
57
Can an alkali be a base?
yes
58
Can a salt be a base?
no
59
What happens in a neutralisation reaction between an acid and an alkali?
Hydrogen ions react with hydroxide ions to produce water
60
What is the equation for the neutralisation of an acid with an alkali?
H+(aq) + OH-(aq) → H2O(l)
61
What are bases that are soluble in water called?
alkalis
62
What are substances that can be used to identify alkalis and acids called?
indicators
63
What colour does methyl orange turn in a strong acid?
red
64
What colour does methyl orange turn in a weak acid?
red
65
What colour does methyl orange turn in water?
orange
66
What colour does methyl orange turn in a weak alkali?
yellow
67
What colour does methyl orange turn in a strong alkali?
yellow
68
What colour does Phenolphthalein solution turn in a strong acid?
colourless
69
What colour does Phenolphthalein solution turn in a weak acid?
colourless
70
What colour does Phenolphthalein solution turn in water?
colourless
71
What colour does Phenolphthalein solution turn in a weak alkali?
pink
72
What colour does Phenolphthalein solution turn in a strong alkali?
pink
73
What colour does Litmus Paper turn in a strong acid?
red
74
What colour does Litmus Paper turn in a weak acid?
red
75
What colour does Litmus Paper turn in water?
No colour change
76
What colour does Litmus Paper turn in a weak alkali?
blue
77
What colour does Litmus Paper turn in a strong alkali?
blue
78
What colour does Universal Indicator Solution turn in a strong acid?
red/PH = 1
79
What colour does Universal Indicator Solution turn in a weak acid?
orange/PH = 5
80
What colour does Universal Indicator Solution turn in water?
green/PH = 7
81
What colour does Universal Indicator Solution turn in a weak alkali?
blue/PH = 10
82
What colour does Universal Indicator Solution turn in a strong alkali?
purple/PH = 14
83
What colour does Universal Indicator paper turn in a strong acid?
red/PH = 1
84
What colour does Universal Indicator paper turn in a weak acid?
orange/PH = 5
85
What colour does Universal Indicator paper turn in water?
green/PH = 7
86
What colour does Universal Indicator paper turn in a weak alkali?
blue/PH = 10
87
What colour does Universal Indicator paper turn in a strong alkali?
purple/PH = 14
88
What is the PH scale?
The PH scale is a scale from 0-14 indicating how alkali or acidic a substance is
89
What is neutral on the PH scale?
7
90
What is PH?
PH is a measure of the concentration of H⁺ ions in a solution
91
The PH scale is logarithmic, what does this mean?
each change in 1 on the scale represents a change in concentration by a factor of 10
92
What is the H⁺ concentration of a substance with a PH of 0?
1x10⁻⁰ mol/dm³
93
What is the H⁺ concentration of a substance with a PH of 1?
1x10⁻¹ mol/dm³
94
What is the H⁺ concentration of a substance with a PH of 2?
1x10⁻² mol/dm³
95
What is the H⁺ concentration of a substance with a PH of 3?
1x10⁻³ mol/dm³
96
What is the H⁺ concentration of a substance with a PH of 4?
1x10⁻⁴ mol/dm³
97
What is the H⁺ concentration of a substance with a PH of 5?
1x10⁻⁵ mol/dm³
98
What is the H⁺ concentration of a substance with a PH of 6?
1x10⁻⁶ mol/dm³
99
What is the H⁺ concentration of a substance with a PH of 7?
1x10⁻⁷ mol/dm³
100
What is the H⁺ concentration of a substance with a PH of 8?
1x10⁻⁸ mol/dm³
101
What is the H⁺ concentration of a substance with a PH of 9?
1x10⁻⁹ mol/dm³
102
What is the H⁺ concentration of a substance with a PH of 10?
1x10⁻¹⁰ mol/dm³
103
What is the H⁺ concentration of a substance with a PH of 11?
1x10⁻¹¹ mol/dm³
104
What is the H⁺ concentration of a substance with a PH of 12?
1x10⁻¹² mol/dm³
105
What is the H⁺ concentration of a substance with a PH of 13?
1x10⁻¹³ mol/dm³
106
What is the H⁺ concentration of a substance with a PH of 14?
1x10⁻¹⁴ mol/dm³
107
Why do strong acids have lower PH's than weak acids?
For 2 acids of equal concentration, where 1 is strong and the other is weak, the strong acid will have a lower PH due to its capacity to dissociate more and hence put more H⁺ ions into solution than weak acid
108
Describe the method for forming copper sulfate crystals
1) Measure out 25cm³ of sulfuric acid using a measuring cylinder and place it in a 100cm³ beaker
2) Gently warm the mixture using a Bunsen burner. do not boil the acid
3) Add a spatula load of copper oxide and stir with a glass rod. After a short time, the black copper oxide will all react producing a blue solution
4) Keep adding the copper oxide 1 spatula at a time until it no longer reacts. You will be able to tell as there will be unreacted black solid in the mixture
5) Filter and wash the mixture in a conical flask
6) While the mixture is filtering, set up a water bath using a half full 250cm³ beaker of water on a gauaze above a Bunsen burner. Start heating the water
7) Once the filtration is complete, transfer some of the filtrate into an evaporating basin (do not fill it over half way)
8) carefully place the basin on the water bath and heat to allow some of the water to evaporate from the copper sulfate solution
9) keep heating until crystal start to appear then stop
10) Place the basin in a cool place for 24 hours
11) After 24 hours record your observations
109
What is the reaction of a metal and an acid?
Metal + acid -> salt + hydrogen
110
What is the reaction of an alkali and an acid?
Alkali (metal hydroxide) + Acid -> water + salt
111
What is the reaction of a carbonate and an acid?
Carbonate + acid -> water + carbon Dioxide + salt
112
What is the reaction of a base and an acid?
Base (metal oxide) + acid -> water + salt
113
What salt is formed with nitric acid and sodium carbonate
sodium nitrate
114
What salt is formed with nitric acid and magnesium
magnesium nitrate
115
What salt is formed with nitric acid and potassium oxide
potassium nitrate
116
What salt is formed with nitric acid and copper hydroxide
copper nitrate
117
What salt is formed with hydrochloric acid and sodium carbonate
sodium chloride
118
What salt is formed with hydrochloric acid and magnesium
magnesium chloride
119
What salt is formed with hydrochloric acid and potassium oxide
potassium chloride
120
What salt is formed with hydrochloric acid and copper hydroxide
copper chloride
121
What salt is formed with sulfuric acid and sodium carbonate
sodium sulfate
122
What salt is formed with sulfuric acid and magnesium
magnesium sulfate
123
What salt is formed with sulfuric acid and potassium oxide
potassium sulfate
124
What salt is formed with sulfuric acid and copper hydroxide
copper sulfate
125
What is the mneumonic for REDOX reactions?
OIL RIG
126
What does OIL RIG stand for?
Oxidation
Is
Loss of electrons
Reduction
Is
Gain of electrons
127
What does REDOX stand for?
Reduction
| Oxidation
128
What is a Reduction reaction?
a reduction reaction is when oxygen is lost but electrons are gained
129
What is an oxidation reaction?
an oxidation reaction is when oxygen is gained and electrons are lost
130
What are the half equations for the equation "2Al + Fe₂O₃ -> Al₂O₃ + 2Fe2
Oxidation = Al⁰ - 3e⁻ -> Al³⁺
| Reduction =Fe³⁺ + 3e⁻ -> Fe⁰
131
What is the ionic equation for the equation "2Al + Fe₂O₃ -> Al₂O₃ + 2Fe2
Al + Fe³⁺ -> Al³⁺ + Fe
132
What are the half equations for the equation "Cu + 2AgNO₃ -> Cu(NO₃)₂ + 2Ag"
```
Oxidation = Cu - 2e⁻ -> Cu²⁺
Reduction = 2Ag⁺ + 2e⁻ -> 2Ag
```
133
What is the ionic equation for the equation "Cu + 2AgNO₃ -> Cu(NO₃)₂ + 2Ag"
Cu + 2Ag⁺ -> Cu²⁺ + 2Ag
134
What are the half equations for the equation "Fe + CuSO₄ -> FeSO₄ + Cu"
```
Oxidation = Fe - 2e⁻ -> Fe²⁺
Reduction = Cu²⁺ + 2e⁻ -> Cu
```
135
What is the ionic equation for the equation "Fe + CuSO₄ -> FeSO₄ + Cu"
Fe + Cu²⁺ -> Fe²⁺ + Cu
136
What is the charge of a silver ion?
1+
137
What is the charge of *most* transition metals?
2+
138
What are the half equations for the equation "Pb + 2AgNO₃ -> Pb(NO₃)₂ + 2Ag"
```
oxidation = Pb - 2e⁻ -> Pb²⁺
reduction = 2Ag⁺ + 2e⁻ -> 2Ag
```
139
What is the ionic equation for the equation "Pb + 2AgNO₃ -> Pb(NO₃)₂ + 2Ag"
Pb + 2Ag⁺ -> Pb²⁺ + 2Ag
140
What is the reactivity series?
```
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold
Platinum
```
141
What elements in the reactivity series are obtained by electrolysis?
Potassium to Aluminium
142
What elements in the reactivity series are obtained by displacing them with carbon?
Zinc to Copper
143
What elements in the reactivity series are obtained by thermal decomposition?
Mercury & silver
144
What elements in the reactivity series are found as elements naturally?
Gold and Platinum
145
What happens to the reactivity as you go down the reactivity series?
it decreases
146
What happens to the difficulty of extracting the elements as you down the reactivity series?
It gets easier to extract the elements
147
Lead is extracted by the reduction of lead oxide by heating with carbon in the equation "PbO + C -> Pb + CO" explain why lead can be extracted this way
Lead can be extracted by heating with carbon as carbon is more reactive than lead. This means that the carbon displaces the lead from the oxide and leaves the lead in pure form.
148
Lead is extracted by the reduction of lead oxide by heating with carbon in the equation "PbO + C -> Pb + CO" explain why this is a REDOX reaction
This is a REDOX reaction as there is both an oxidation and a reduction. The lead is undergoing a reduction reaction, this is because it is gaining electrons but losing oxygen. The carbon is being oxidised as it is losing electrons but gaining oxygen
149
What is a metallic bond?
The electrostatic attraction between the positive metal ions and the negative sea of valence delocalised electrons
150
What is the structure of a metal
A giant metallic lattice
151
Why do metals have high boiling points?
They have high melting points as they have many strong metallic bonds that need to be broken for them to melt/evaporate. This means that a lot of energy is required to break these bonds
152
Why are metals malleable and ductile?
Metals are malleable and ductile as they have layers of metal ions that can slide over each other, due to their structure they do not repel each other
153
Why are metals good conductors of thermal and electrical heat?
They have charged particles (delocalised electrons) that can move freely throughout the whole structure
154
What type of ions do metals form?
cations (positive ions)
155
What factors affect how readily metal atoms lose its outer shell electrons?
* The number of electrons in the outer shell
* Distance of outer shell electrons from the nucleus
* Electrons shielding
156
How does the number of electrons in the outer shell affect how readily metal atoms lose its outer shell electrons?
it is easier to lose 1 electron (ie group 1 metals) than 2 electrons (ie group 2 metals)
157
How does distance of outer shell electrons from the nucleus affect how readily metal atoms lose its outer shell electrons?
The bigger the atom, the easier it is to lose electrons as the attraction of the nucleus on the valence electrons is not as strong
158
How does electrons shielding affect how readily metal atoms lose its outer shell electrons?
The greater the number of shielding electrons, the weaker the nuclear attraction on the outer electrons, the easier it is to lose
159
What is the word equation of group 1 metals and water?
metal + water -> metal hydroxide + hydrogen
160
What is the reaction of potassium to calcium with water?
fizz, giving off hydrogen gas, leaving an alkaline solution of metal hydroxide
161
What is the reaction of magnesium to iron with water?
very slow reaction
162
What is the reaction of tin to lead with water?
slight reaction with steam
163
What is the reaction of copper to platinum with water?
no reaction, even with steam
164
What is the reaction of potassium to lithium with a dilute acid?
explodes, too dangerous
165
What is the reaction of calcium to iron with a dilute acid?
fizz, giving off hydrogen and forming a salt
166
What is the reaction of tin to lead with a dilute acid?
react slowly with warm acid
167
What is the reaction of copper to platinum with a dilute acid?
no reaction
168
What is the mnemonic for the reactivity series?
Please Send Lions, Cats, Monkeys, And, Crazy, Zebras Into The Largest Hat Cafe, Signed General Penguin
169
How do you remember neutralisation reactions?
MASH
AAWS
CAWCS
BAWS
170
What does MASH stand for?
Metal + Acid -> Salt + Hydrogen
171
What does AAWS stand for?
Acid + Alkali -> Water + Salt
172
What does CAWCS stand for?
Carbonate + Acid -> Water + Carbon Dioxide + Salt
173
What does BAWS stand for?
Base (Metal Oxide) + Acid -> Water + Salt
174
Why is the conical flask placed on a white tile during titration?
To more clearly see the colour change of the indicator solution, therefore achieving more accurate results as your data collected will be more accurate to the real end point
175
Why is it not necessary to dry the conical flask before titration after washing it with distilled water?
The water does not affect the number of moles of alkali in the flask, therefore the same volume of acid is required to neutralise it, therefore your results are not affected
176
Describe how a pipette is prepared and used for titration?
First you must collect all your necessary equipment and ensure that you are wearing safety goggles. Rinse the pipette with deionised water and then rinse with your alkali solution whilst twisting the pipette to unsure you wash all the sides of the pipette. Attach the pipette filler to the end of the pipette, and place the other end of the pipette in the alkali solution. Use the pipette filler to fill the pipette until the bottom of the meniscus of the alkali lies on the desired volume. Release the alkali solution into the conical flask using the pipette filler
