Topic 5a Mass calculations, electrolysis, extraction of metals and equilibria Flashcards
(143 cards)
1
Q
- What is the formula of water?
A
H2O
2
Q
- What is the formula of sodium chloride?
A
NaCl
3
Q
- What is the formula of carbon dioxide?
A
CO2
4
Q
- The formula of magnesium chloride is MgCl2. What is the ratio of magnesium ions to chloride ions?
A
1:2
5
Q
- The formula of sulfuric acid is H2SO4. How many atoms of each element are in the formula?
A
H = 2, S = 1, O = 4
6
Q
- The formula of calcium nitrate is Ca(NO3)2. How many calcium, nitrogen and oxygen atoms are in the formula?
A
Ca = 1, N = 2, O = 6
7
Q
- There are two numbers alongside chlorine in the periodic table, 17 and 35.5. What does the number 17 represent?
A
atomic number
8
Q
- What does the number 35.5 represent?
A
relative atomic mass
9
Q
- Sodium chloride has the formula NaCl. The relative atomic mass of sodium is 23 and that of chlorine is 35.5. What is the relative formula mass of NaCl?
A
58.5
10
Q
- A water molecule has the formula H2O. The relative atomic mass of hydrogen is 1 and that of oxygen is 16. What is the relative formula mass of a molecule of water?
A
18
11
Q
- What is the symbol for relative atomic mass?
A
Ar or RAM
12
Q
- What is the symbol for relative formula mass?
A
Mr or RFM
13
Q
- The relative atomic mass of hydrogen is 1. What is the relative formula mass of hydrogen molecules?
A
2
14
Q
- Sodium chloride has the formula NaCl; the relative atomic mass of sodium is 23 and that of chlorine is 35.5. What is the relative formula mass of NaCl?
A
58.5
15
Q
- A water molecule has the formula H2O; the relative atomic mass of hydrogen is 1 and that of oxygen is 16. What is the relative formula mass of water?
A
18
16
Q
- A carbon dioxide molecule has the formula CO2; the relative atomic mass of carbon is 12 and that of oxygen is 16. What is the relative formula mass of carbon dioxide?
A
44
17
Q
- What is the empirical formula of a compound with molecular formula C2H4?
A
CH2
18
Q
- What is the empirical formula of a compound with molecular formula C3H8?
A
C3H8
19
Q
- A sample of magnesium carbonate was heated in an open test tube. Why did it lose mass?
A
gas/carbon dioxide escaped
20
Q
- 100 cm3 of a solution contained 2 g of salt. What is the concentration of the salt in g dm-3?
A
20
21
Q
- A sample of copper carbonate was heated in an open test tube. Why did it lose mass?
A
gas/carbon dioxide escaped
22
Q
- Why does magnesium increase in mass when it is heated in air?
A
combines with oxygen
23
Q
- How many cm3 are there in 1 dm3?
A
1000
24
Q
- What is 250 cm3 expressed in dm3?
A
0.25
25
25. What is 0.5 dm3 expressed in cm3?
500
26
26. 100 cm3 of a solution contains 1.5 g of salt. What is the concentration of the salt solution in g dm3?
15
27
27. 250 cm3 of a solution contains 5 g of sugar. What is the concentration of the sugar solution in g dm3?
20
28
28. A solution of copper sulfate has concentration 10 g dm3. What mass of copper sulfate will be dissolved in 100 cm3 of solution?
1 g
29
29. 2 g of hydrogen reacts with oxygen to form 18 g of water. What mass of water will be formed from 1 g of hydrogen?
9 g
30
30. 2H2 + O2 → 2H2O. How many molecules of hydrogen are needed to react with 1 dozen molecules of oxygen to form water?
2 dozen
31
31. What is the abbreviation used for the mole, the unit for amount of substance?
mol
32
32. How many particles are there in 1 mole of particles?
6.02 x 1023
33
33. The mass of 1 mole of carbon atoms is 12 g. What is the mass of 2 moles of carbon atoms?
24 g
34
34. What is the formula for calculating the number of moles of substance from its mass in g
moles = mass (g) / RAM or RFM
35
35. Each water molecule contains three atoms. How many moles of atoms are there in 2 moles of water molecules?
6 mol
36
36. The relative formula mass of chlorine gas is 71. What is the mass of 1 mole of chlorine gas?
71 g
37
37. What is the Avogadro number?
6.02 x 1023 the number of atoms/particles in a mole
38
38. What is the emperical formula of a compound?
The simplist whole number ratio of atoms in compound
39
39. What is the law of conservation of mass?
total mass of reactants = total mass of products
40
40. How are the emperical formula and molecular formula related?
The molecular formula is a multiple of the emperical formula
41
41. What name is given to an atom that has gained or lost electrons?
ion
42
42. What type of charge is on metal and hydrogen ions?
positive
43
43. What type of charge is on most non-metal ions?
negative
44
44. What is another name for a positive ion?
cation
45
45. What is another name for a negative ion?
anion
46
46. What is the symbol for a sodium ion?
Na+
47
47. What is the symbol for a magnesium ion?
Mg2+
48
48. What is the symbol for a chloride ion?
Cl-
49
49. What is the symbol for a sulfate ion?
SO42-
50
50. In what states do ionic compounds conduct electricity?
when molten or dissolved in water
51
51. Which of these is not an electrolyte: solid sodium chloride, molten sodium chloride, aqueous sodium chloride?
solid sodium chloride
52
52. What is the name of the positively charged electrode?
anode
53
53. What type of ions are attracted to the positively charged electrode?
anions / negative ions
54
54. What is the name of the negatively charged electrode?
cathode
55
55. What type of ions are attracted to the negatively charged electrode?
cations / positive ions
56
56. H What process takes place when a substance gains electrons?
reduction
57
57. H In terms of subatomic particles, what happens to a substance when it is oxidised?
It loses electrons.
58
58. H What type of reaction takes place at the anode during electrolysis?
oxidation
59
59. What are inert electrodes made from?
graphite / platinum
60
60. What is produced at the cathode when molten lead bromide is electrolysed?
lead
61
61. What gas is formed when sodium reacts with water?
hydrogen
62
62. What solution is formed when sodium reacts with water?
sodium hydroxide
63
63. What colour is universal indicator when added to sodium hydroxide?
blue or purple
64
64. What gas is formed when magnesium is added to dilute sulfuric acid?
hydrogen (MASH)
65
65. What solution is formed when magnesium reacts with dilute sulfuric acid?
magnesium sulfate
66
66. What would you see when magnesium is added to dilute sulfuric acid?
effervescence/fizzing/bubbles/magnesium disappears
67
67. Name a metal that does not react with water or dilute acids.
copper/silver/gold/platinum
68
68. What products are formed when zinc is added to copper sulfate solution?
zinc sulfate and copper
69
69. What type of reaction takes place when zinc is added to copper sulfate solution?
displacement
70
70. Magnesium reacts with chromium nitrate solution to form magnesium nitrate and chromium. Which metal is more reactive?
magnesium
71
71. Name a metal that reacts vigorously with cold water.
potassium/sodium/rubidium/caesium/lithium/calcium
72
72. What gas is produced when a metal reacts with water?
hydrogen
73
73. How do you test for the hydrogen gas?
It pops a lighted splint.
74
74. What type of solution is formed when a metal reacts with water - acidic, alkaline or neutral?
alkaline
75
75. What salt is formed when zinc reacts with hydrochloric acid?
zinc chloride
76
76. Complete the word equation, magnesium + copper sulfate makes ...
copper + magnesium sulfate
77
77. What type of ions are formed from metal atoms when they react with acids?
cations/positive ions
78
78. What type of reaction takes place when a substance loses oxygen?
reduction
79
79. Name a metal that occurs uncombined in the Earths crust.
gold/silver/platinum
80
80. Name a metal that could be extracted from its metal oxide by heating with carbon.
zinc/iron/copper
81
81. Name a metal that occurs uncombined in the Earths crust.
gold/silver/platinum
82
82. Name a metal, other than iron, that could be extracted from its metal oxide by heating with carbon.
zinc/copper
83
83. What compound of carbon is formed when it is heated with copper oxide?
carbon dioxide/carbon monoxide
84
84. Why is electrolysis not used to extract iron from iron oxide?
too expensive/too much energy needed
85
85. Why is aluminium not extracted by heating aluminium oxide with carbon?
aluminium is more reactive than carbon/carbon is not reactive enough to remove the oxygen
86
86. What is the aluminium oxide dissolved in to form the electrolyte for electrolysis?
molten cryolite
87
87. What are the electrodes made from?
carbon/graphite
88
88. At which electrode is the aluminium produced?
cathode/negative electrode
89
89. What type of reaction takes place when a metal is extracted from its ore?
reduction/redox
90
90. What type of reaction takes place when a metal corrodes?
oxidation/redox
91
91. What is the definition of oxidation, in terms of oxygen?
gain of oxygen
92
92. H What is the definition of oxidation, in terms of electrons?
loss of electrons
93
93. What type of reaction takes place when metals are extracted from their ores?
reduction/redox
94
94. What is the specific name for the corrosion of iron?
rusting
95
95. Which of these metals will corrode most quickly - iron, sodium, copper?
sodium
96
96. Why does sodium corrode most quickly.
most reactive metal corrodes most quickly
97
97. Which substance has been oxidised in this reaction - copper oxide + hydrogen → copper + water?
hydrogen
98
98. Which substance has been reduced in in this reaction - copper oxide + hydrogen → copper + water?
copper oxide
99
99. What name is given to a process that converts an unwanted product into a new, useful product?
recycling
100
100. Name a type of substance that can be recycled.
metal, plastic, paper, cardboard, glass, etc.
101
101. What can happen in a reversible reaction?
the products can reform the reactants
102
102. What does the term equilibrium describe?
a position of balance
103
103. What is the process used to make ammonia?
Haber Process
104
104. What is the molecular formula of ammonia?
NH3
105
105. What is the balanced symbol equation for making ammonia from Nitrogen (N2) and Hydrogen (H2)
N2 +3H2 → 2NH3
106
106. Where does nitrogen come from for use in the Haber Process?
From the fractional distillation of air
107
107. Where does Hydrogen come from for use in the Haber process?
From methane from crude oil
108
108. What conditions of pressure are required to increase the yield of ammonia in the Haber Process?
High pressure (because there are more molecules on the LHS of the equation)
109
109. The forward reaction is exothermic. What conditions of temperature are required to increase the yield of ammonia in the Haber Process?
Low temperature (The equilibrium will shit to try and produce heat)
110
110. Theoretically, a high yield of ammonia is produce at low temperature and high pressure. Why is this not used in reality?
Low temperatue will result in a slow rate of reaction. High pressures are expensive and dangerous.
111
111. It was found that metal X didn’t react with dilute acids. What does this definitely tell us about the position of Metal X in the reactivity series?
It is below hydrogen in the reactivity series. This is because metals above hydrogen can displace hydrogen from dilute acids.
112
112. What happens at the positive anode always?
Oxidation
113
113. What happens at the negative cathode always?
Reduction
114
114. Most metals can be extracted from their ores by electrolysis. What is the main reason that copper metal isn’t extracted from its ore by electrolysis?
The main reason that copper metal isn’t extracted from its ore by electrolysis is that the process uses a lot of electrical energy. Many extraction methods produce unwanted waste gases anyways.
115
115. What factor does the biological extraction of copper, using phytoextraction, depend on?
That plants can take in copper compounds from the soil
Phytoextraction concentrates the copper in the plant, which is collected and burned. The metal can be obtained from the ash.
116
116. When a metal is extracted from its ore using carbon, what is oxidised?
The carbon is oxidised as it gains oxygen.
The metal oxide is reduced.
117
117. What products are formed when zinc metal reacts with steam?
Metal + steam → metal oxide + hydrogen.
Hydroxides are formed in the reactions of metals with liquid water.
118
118. What conditions of temperature and pressure are used in the industrial manufacture of ammonia?
temperature = 450 °C
pressure = 200 atmospheres.
119
119.
## Footnote
One of the stages in sulfuric acid production is described by this equation:
2SO2(g) + O2(g) ⇌ 2SO3(g).
What will happen to the yield of SO3 if the pressure is increased?
If the pressure is increased, the SO3 yield will go up as the equilibrium position moves in the direction which forms less molecules of gas.
120
120. If the forward reaction in a reversible reaction is endothermic, what will be the effect of decreasing the temperature?
The effect of decreasing the temperature would be to decrease the amount of products at equilibrium as the equilibrium position moves in the backward direction which is exothermic.
121
121.
## Footnote
What is the effect of decreasing the pressure on the following equilibrium:
2NO(g) + O2(g) ⇌ 2NO2(g)?
The effect of increasing the pressure is to produce less NO2, as the equilibrium shifts in the direction which produces more gas molecules.
122
122. What effect on the equilibrium position is produced by adding a catalyst to a system in equilibrium? - Higher
Adding a catalyst has no effect on the position of equilibrium so the yield of products is unchanged.
123
123. When is an equilibria acheived in a closed or open system?
Closed so none of the products or reactants can escape.
124
124. What is an electrolyte?
An ionic compound either dissolved in solution or molten
125
125. What is an electrode?
The material used to supply electricity to the electrolyte (usually carbon or platinum)
126
126. In the elctrolysis of copper sulphate, the electrodes are made of copper. Which decreases and increases in weight?
The anode decreases in weight.
The cathode increases in weight.
Copper is transferred from the anode to the cathode.
127
What are the equations at the electrodes in the elctrolysis of copper sulphate using copper electrodes?
Equations at electrodes (HIGHER)
At the Cathode
Cu2+ + 2e- → Cu This is Reduction
At the Anode
Cu - 2e- → Cu2+ This is Oxidation
128
128. What are the rules for what is produced in electrolysis?
Rules for competition at electrodes
At the cathode – the least reactive metal will win
At the anode – the least complex ion will win
Halide \> Hydroxide \> all other negative ions
129
129. What is the order of the reactivity series?
130
In the electrolysis of copper sulphate using INERT ELECTRODES, What is formed at the anode and cathode? And why?
Ions present : Cu2+ , H+ , OH- , SO42-
At the cathode (Copper) Cu2+ + 2e- → Cu Red.
At the anode (Oxygen) 4OH– – 4e– → O2 + 2H2O Ox.
Because
Copper is less reactive than hydrogen so is formed
OH- is a more simple ion than SO42- so oxygen is formed
131
131. What are the metals you can and can't extrct from their ores.
132
132. How can you extract copper from it's ore?
heating (smelting)
Bio leaching
Phytomining
133
What is bio leaching?
Uses bacteria to concentrate the copper called a leachate.
copper is extracted from the lechate by displacement using scrap ion, then purified by electrolysis.
134
What is Phytoextraction/ Phytomining?
Uses plants to concentrate the copper. The plants absorb the metal compounds then the plants are burnt to form ash, from which the metal is extracted.
135
What are the advantages and disvantages of bioleaching?
does not require high temperatures
toxic substances and sulphuric acid can be produced by the process, and damage the environment.
136
What are the pros and cons of phytoextraction/mining?
can extract metals from contaminated soils
more expensive than mining some ores. growing plants is dependent on weather conditions.
137
Pros and cons of using both bio leaching and pytoextraction/mining?
no harmful gases are produced.
causes less damage to the landscape than mining.
conserves supplies of higher garde ores.
very slow process.
138
When extracting aluminium or metals using electrlysis what is produced at the cathode and anode?
Ions present : Al3+ , O2-
At the cathode (Aluminium)
Al3+ + 3e- → Al
At the anode (Oxygen)
2O2– – 4e– → O2
139
What is the balanced making ammonia The haber process equation?
N2 (g) + 3H2 (g) 2NH3 (g) + Heat
140
What three factors effect the posistion of the equilibrium?
(not catalysts they only speed up the process)
temperature
pressure
concentration?
141
What are the effects of concentration, pressure and temperature on the position of an equilibrium.
1 concentration
If the concentration of reactant is increased more products are made to use them up.
If the concentration of products are decreased more products will be made to replace them.
2 pressure
If the pressure is increased the equilibrium will shift to the side of the reaction with less molecules of gas to try to reduce the pressure.
3 temperature
If the temperature is decreased the equilibrium will shift to the side that produces heat to try to heat it up.
142
what is the catalyst used in the haber process?
Iron catalyst.
143
