Chemical changes Flashcards
(112 cards)
1
Q
What is the pH scale?
A
It is a measure of how acidic or alkaline a solution is.
2
Q
If a substance is greater than 7 what does this mean?
A
It is more alkaline.
3
Q
If a substance is less than 7 what does this mean?
A
It is more acidic
4
Q
The further away the substance is from 7 what does it mean?
A
the stronger the acid or alkaline.
5
Q
What is the pH of a neutral substance?
A
pH7
6
Q
Give an example of a Neutral substance.
A
Pure water
7
Q
From pH 1 to 6 what is the colour on uniserval indicator?
A
Dark red to orange.
8
Q
What colour on universal indicator is a neutral substance?
A
Green
9
Q
From pH 8to 14 what is the colour on uniserval indicator?
A
green to dark blue
10
Q
What are the two ways to measure pH of a solution?
A
1) pH probe
2) indicator of universal indicator.
11
Q
What is a Universal indicator?
A
It gives you pH measurement based on color on chart
12
Q
What is a pH probe?
A
A digital device which is put in a beaker and give you a reading in number
13
Q
What is an Acid?
A
it is a substance that dissolved in water to produce H+ ions it has a pH of less than 7.
14
Q
What is a base?
A
it is a substance with a pH greater than 7.
15
Q
What is an Alkaline?
A
It is a base that dissolves in water to produce hydroxide ions (OH-) it has a pH of greater than 7.
16
Q
What are the reactions between acids and bases called?
A
Neutralization
17
Q
What is the reaction for Neutralization?
A
Acid + base —– salt + water
18
Q
In terms of H+ ions and OH- ions what is the neutralization reaction?
A
H+(aq) + OH- (aq) —- H20(l)
19
Q
Sodium hydroxide and hydrochloric acid react to produce sodium chloride and
water. Name the type of reaction described
A
Neutralization
20
Q
Explain, in terms of ions and molecules, what happens when any acid reacts with
any alkali.
A
Hydrogen ions/H+ in the acid React with hydroxide ions OH- in the alkali to produce water.
21
Q
Ammonium chloride is a useful substance made by a similar reaction to the above. Name the acid that would be used to form ammonium chloride.
A
hydrochloric acid
22
Q
Hydrochloric acid produces what?
A
chlorides
23
Q
What does nitric acid produces?
A
nitrates
24
Q
What does sulfuric acid produce?
A
sulfates
25
Sodium hydroxide breaks down into what?
Sodium ions and hydroxide ions when dissolved in water.
26
In aqueous solution what do acid molecules do?
They ionize (split ) and release H+ ions
27
What is a strong acid?
They fully ionize in aqueous solutions (every acid molecule splits to release H+ ions)
28
How do you know the reaction with hydrogen and chloride produces a strong acid HCI (aq) ---- H+(aq) +Cl-(aq)
The arrow goes in one direction, telling us that the acid has fully ionised.
29
Name 3 examples of Strong acids.
Sulfuric acid
Nitriic acid
Hydrochloric acid
30
What is a weak acid?
The acid partially ionises in aqueous solutions ( only a small proportion of acid particles release H+ ions.
31
How do you a weak acid is being formed in a word equation?
It has a reversible reaction arrow telling us it is a weak acid.
32
Name 3 examples of Weak acid.
Carbonic acid
Ethanoic acid
Citric acid
33
What is concentration?
it is a measurement of how much a soluble substance is dissolved in a solvent.
34
What is concentration measured in?
grams per dm 3 or moles per dm 3
35
What is the relationship of the pH scale and concentration of hydrogen ions?
the pH scale gives us an idea of the concentration of hydrogen ions (H+)
36
A strong acid has a pH of what?
1 2 and 3
37
A weak acid has a pH of what?
4 5 and 6
38
Why is a weak acid closer to neutral?
it is closer to neutral as they don't release as many H+ ions as strong acids do.
39
The more H+ ions in a solution means what?
The lower the pH
40
What is the concentration in mol/dm3 of H+ ions in a pH of 1?
0.1
41
What is the concentration in mol/dm3 of H+ ions in a pH of 2?
0.01
42
What is the concentration in mol/dm3 of H+ ions in a pH of 3?
0.001
43
What is the concentration in mol/dm3 of H+ ions in a pH of 4?
0.0001
44
What is the concentration in mol/dm3 of H+ ions in a pH of 5?
0.00001
45
What is the concentration in mol/dm3 of H+ ions in a pH of 6?
0.000001
46
To get from a pH 6 to pH 5 what do you have to do?
times by 10
47
How much concentrated is pH 1 than pH 6?
100,000
48
If the pH scale decreases by one unit what does this mean?
The concentration of hydrogen increases by 10.
49
A dilute (less water) acid will have what?
will have fewer acid molecules in a given volume than a concentrated.
50
Concentrated acids have what compared to a dilute acid?
A lower pH than dilute acids.
51
Why can an acid have a low pH and is very acidic?
This is because it contains a high concentration of H+ ions.
52
Nitric acid with a concentration of 1mol/dm3 has a pH of 1.
A student diluted 25cm3 of the acid with same volume of water.
What effect would this have on the pH of the acid?
pH would increase (become less acidic) because there is a lower concentration of H+ ions.
53
Sodium hydroxide neutralises nitric acid.Write a balanced symbol equation or this neutralisation reaction.
NaOH + HNO3⟶ NaNO3 + H2O
54
Write a chemical equation for the reaction between magnesium and steam?
Mg + H2O → MgO + H2
55
A student added strong acid to a weakly acidic solution of pH6. The pH of the new solution was found to be pH 3. By how many times did the concentration of H+ increase?
1000
56
All metal oxides and hydroxides will what to acids?
Neutralise acids
57
Bases and alkali can react with water by neutralizing them to produce what?
Salt and water
58
Acids + Metal oxide produces ?
Salt + water
59
Acid + Metal hydroxide produces ?
Salt + water
60
What is the chemical formula for Hydrochloric acid?
HCI
61
What is the chemical formula for Sulfuric acid?
H2SO4
62
What is the chemical formula for Nitric acid?
HN03
63
Hydrochloric acid produces what?
Chlorides
64
What does nitric acid produces?
Nitrates
65
What does sulfuric acid produce?
sulfates
66
Hydrochloric acid + copper oxide produces what?
Copper chloride + water
67
Sulfuric acid + potassium hydroxide produces what?
Potassium sulfate + Water
68
nitric acid + sodium hydroxide produces what?
Sodium nitrate + water
69
HCI + Cu0 produces what?
CuCI2 + H20
70
H204 + KOH produces what?
K2SO4 + water
71
HN03 + NaOH produces what?
NaN03 + H20
72
Metal carbonate is an example of what?
A base
73
Acid + Metal carbonate produces what?
Salt + water + carbon dioxide
74
Why does the reaction with Acid + carbonate also produces Carbon dioxide?
Because the metal has a carbonate as part of its compound.
75
Predict the name of the salt that will be formed when Iron oxide + sulphuric acid?
and Magnesium hydroxide + hydrochloric acid
Iron suplate + water
| Magnesium chloride + water
76
Hydrochloric acid + sodium carbonate produces what?
sodium chloride + water + carbon dioxide
77
What is chemical formula for sodium carbonate?
Na2CO3
78
sulfric acid + calcium carbonate produces what?
Calcium sulfate + water + carbon dioxide.
79
What is chemical formula for calcium carbonate
CaCO3
80
What is the chemical formula for Calcium sulfate?
CaSO4
81
What is the method of making soluble salts using insoluble base?
1) Weigh the oxide or carbonate using a balance
2) Measure the acid in measuring cylinder
3) Pour acid into a beaker and add the oxide or carbonate (insoluble base) and mix them together to make sure they react.
4) The solid must be in excess so all the acid is used.
5) Filter off the excess solid using a funnel and filter paper
6) Add the filtrate (liquid) to an evaporating basin and heat until salt is being formed
7) Turn off Bunsen and allow the water to evaporate leaving behind salt crystals, dry in a desiccator
82
What colour is copper oxide and when it is added to acid what colour does it turn?
It is a black powder the solution will turn blue.
83
What could you have done to improve this experiment?
Heat the acid to increase the rate and speed of reaction
84
How would you know the carbonate or oxide is in access?
It stops disappearing
85
Why is the mixture filtered?
To remove excess oxide or carbonate.
86
Why do crystals form when the hot saturated solution is cooled?
The crystals are less soluble in cold water than in hot water.
87
The crystals are removed by filtration and then dried. Suggest a suitable method of drying the crystal?
A kitchen towel
88
What is the reactivity series?
It is a list of metals in order of their reactivity towards other substances.
89
The more higher up the metal is on the reactivity series what does it mean?
The more easily they form positive ions and the easier it reacts with an acid or water.
90
What is the Mnemonic to learn the reactivity series?
```
Please
Send
Little
Charlie
My
Cold
Zebra
In
Hot
Clothes
```
91
What is the actual reactivity series?
```
Potassium
Sodium
Lithium
Calcium
Magnesium
Carbon
Zinc
Iron
Hydrogen
Copper
```
92
What are the 4 very reactive metals in the reactivity series?
Potassium
Sodium
Lithium
Calcium
93
What are the 4 fairly reactive elements in the reactivity series?
Magnesium
Carbon
Zinc
Iron
94
What are the 2 not very reactive elements in reactivity series?
Hydrogen
| Copper
95
Metal +water produces what?
Metal hydroxide + Hydrogen
96
Potassium + water produces what?
Potassium hydroxide + hydrogen
97
What is chemical formula for Calcium + water --- Calcium hydroxide + water
Ca(s) + H20(l) ---- Ca (OH)2(aq) + H2(g)
98
What are the 4 metals that will react with water?
Potassium. sodium, lithium and calcium
99
Will zinc, iron and copper react with water?
No they will not react with water.
100
Acid + metal produces what?
Salt + hydrogen
101
How do you know whether the reaction of a metal and acid is reactive?
1) The more reactive the metal the faster the reaction will go e.g Potassium reacts vigorously
2) The speed of the reaction is indicated by the rate at which bubbles of hydrogen are given off.
102
How can you investigate the reactivity of metals?
By measuring the temperature change of the reaction with an acid or water.
103
Give word and symbol equation for Magnesium + Hydrochloric acid?
1) Magnesium chloride + hydrogen
| 2) MgCL2(whenever reaction with hydrochloric acid it is always Cl2) (aq) + H2(aq)
104
What are ores?
it is a type of rock that contains metal compounds.
105
Lots of metals such as aluminium react with to form what?
metal oxides, this is called oxidation
106
A reaction that separated a metal from its oxide is called what?
A reduction reaction
107
Explain what happens here when Magnesium reacts with oxygen. Give symbol equation as well.
Magnesium is oxidized to make magnesium oxide
| Mg + 02 ---- Mg0
108
Explain what happens when copper is reacted with carbon
Copper oxide is reduced to form copper
| Cu0 + C -- Cu + C02
109
Some metals can be extracted by reduction with what?
| give an example?
By carbon e.g. Iron oxide(Fe2Co3) + carbon ---- iron + carbon dioxide
110
Metals higher than carbon in the reactivity series ( Potassium, sodium, Lithium, Calcium and magnesium) can be extracted by what?
Using electrolysis
111
Metals blow carbon (Zinc, Iron and Copper) can be extracted how?
by reduction using carbon, this is because carbon can only take the oxygen away from metals which are less reactive than carbon itself.
112
Write the word eqaution for the reduction of Zinc oxide (Zn0) by carbon
Zinc oxide + carbon ---- zinc + carbon dioxide
