Topic 5a Mass calculations, electrolysis, extraction of metals and equilibria

Question 1

1. What is the formula of water?

Answer 1

H₂O

Question 2

2. What is the formula of sodium chloride?

Answer 2

NaCl

Question 3

3. What is the formula of carbon dioxide?

Answer 3

CO2

Question 4

4. The formula of magnesium chloride is MgCl₂. What is the ratio of magnesium ions to chloride ions?

Answer 4

1:2

Question 5

5. The formula of sulfuric acid is H₂SO₄. How many atoms of each element are in the formula?

Answer 5

H = 2, S = 1, O = 4

Question 6

6. The formula of calcium nitrate is Ca(NO₃)₂. How many calcium, nitrogen and oxygen atoms are in the formula?

Answer 6

Ca = 1, N = 2, O = 6

Question 7

7. There are two numbers alongside chlorine in the periodic table, 17 and 35.5. What does the number 17 represent?

Answer 7

atomic number

Question 8

8. What does the number 35.5 represent?

Answer 8

relative atomic mass

Question 9

9. 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?

Answer 9

58.5

Question 10

10. 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?

Answer 10

18

Question 11

11. What is the symbol for relative atomic mass?

Answer 11

Ar or RAM

Question 12

12. What is the symbol for relative formula mass?

Answer 12

Mr or RFM

Question 13

13. The relative atomic mass of hydrogen is 1. What is the relative formula mass of hydrogen molecules?

Answer 13

2

Question 14

14. 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?

Answer 14

58.5

Question 15

15. 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?

Answer 15

18

Question 16

16. 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?

Answer 16

44

Question 17

17. What is the empirical formula of a compound with molecular formula C₂H₄?

Answer 17

CH₂

Question 18

18. What is the empirical formula of a compound with molecular formula C₃H₈?

Answer 18

C₃H₈

Question 19

19. A sample of magnesium carbonate was heated in an open test tube. Why did it lose mass?

Answer 19

gas/carbon dioxide escaped

Question 20

20. 100 cm³ of a solution contained 2 g of salt. What is the concentration of the salt in g dm^-3?

Answer 20

20

Question 21

21. A sample of copper carbonate was heated in an open test tube. Why did it lose mass?

Answer 21

gas/carbon dioxide escaped

Question 22

22. Why does magnesium increase in mass when it is heated in air?

Answer 22

combines with oxygen

Question 23

23. How many cm³ are there in 1 dm³?

Answer 23

1000

Question 24

24. What is 250 cm³ expressed in dm³?

Answer 24

0.25

Question 25

25. What is 0.5 dm³ expressed in cm³?

Answer 25

500

Question 26

26. 100 cm³ of a solution contains 1.5 g of salt. What is the concentration of the salt solution in g dm³?

Answer 26

15

Question 27

27. 250 cm³ of a solution contains 5 g of sugar. What is the concentration of the sugar solution in g dm³?

Answer 27

20

Question 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?

Answer 28

1 g

Question 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?

Answer 29

9 g

Question 30

30. 2H₂ + O₂ → 2H₂O. How many molecules of hydrogen are needed to react with 1 dozen molecules of oxygen to form water?

Answer 30

2 dozen

Question 31

31. What is the abbreviation used for the mole, the unit for amount of substance?

Answer 31

mol

Question 32

32. How many particles are there in 1 mole of particles?

Answer 32

6.02 x 10²³

Question 33

33. The mass of 1 mole of carbon atoms is 12 g. What is the mass of 2 moles of carbon atoms?

Answer 33

24 g

Question 34

34. What is the formula for calculating the number of moles of substance from its mass in g

Answer 34

moles = mass (g) / RAM or RFM

Question 35

35. Each water molecule contains three atoms. How many moles of atoms are there in 2 moles of water molecules?

Answer 35

6 mol

Question 36

36. The relative formula mass of chlorine gas is 71. What is the mass of 1 mole of chlorine gas?

Answer 36

71 g

Question 37

37. What is the Avogadro number?

Answer 37

6.02 x 10²³ the number of atoms/particles in a mole

Question 38

38. What is the emperical formula of a compound?

Answer 38

The simplist whole number ratio of atoms in compound

Question 39

39. What is the law of conservation of mass?

Answer 39

total mass of reactants = total mass of products

Question 40

40. How are the emperical formula and molecular formula related?

Answer 40

The molecular formula is a multiple of the emperical formula

Question 41

41. What name is given to an atom that has gained or lost electrons?

Answer 41

ion

Question 42

42. What type of charge is on metal and hydrogen ions?

Answer 42

positive

Question 43

43. What type of charge is on most non-metal ions?

Answer 43

negative

Question 44

44. What is another name for a positive ion?

Answer 44

cation

Question 45

45. What is another name for a negative ion?

Answer 45

anion

Question 46

46. What is the symbol for a sodium ion?

Answer 46

Na+

Question 47

47. What is the symbol for a magnesium ion?

Answer 47

Mg²⁺

Question 48

48. What is the symbol for a chloride ion?

Answer 48

Cl^-

Question 49

49. What is the symbol for a sulfate ion?

Answer 49

SO₄^2-

Question 50

50. In what states do ionic compounds conduct electricity?

Answer 50

when molten or dissolved in water

Question 51

51. Which of these is not an electrolyte: solid sodium chloride, molten sodium chloride, aqueous sodium chloride?

Answer 51

solid sodium chloride

Question 52

52. What is the name of the positively charged electrode?

Answer 52

anode

Question 53

53. What type of ions are attracted to the positively charged electrode?

Answer 53

anions / negative ions

Question 54

54. What is the name of the negatively charged electrode?

Answer 54

cathode

Question 55

55. What type of ions are attracted to the negatively charged electrode?

Answer 55

cations / positive ions

Question 56

56. H What process takes place when a substance gains electrons?

Answer 56

reduction

Question 57

57. H In terms of subatomic particles, what happens to a substance when it is oxidised?

Answer 57

It loses electrons.

Question 58

58. H What type of reaction takes place at the anode during electrolysis?

Answer 58

oxidation

Question 59

59. What are inert electrodes made from?

Answer 59

graphite / platinum

Question 60

60. What is produced at the cathode when molten lead bromide is electrolysed?

Answer 60

lead

Question 61

61. What gas is formed when sodium reacts with water?

Answer 61

hydrogen

Question 62

62. What solution is formed when sodium reacts with water?

Answer 62

sodium hydroxide

Question 63

63. What colour is universal indicator when added to sodium hydroxide?

Answer 63

blue or purple

Question 64

64. What gas is formed when magnesium is added to dilute sulfuric acid?

Answer 64

hydrogen (MASH)

Question 65

65. What solution is formed when magnesium reacts with dilute sulfuric acid?

Answer 65

magnesium sulfate

Question 66

66. What would you see when magnesium is added to dilute sulfuric acid?

Answer 66

effervescence/fizzing/bubbles/magnesium disappears

Question 67

67. Name a metal that does not react with water or dilute acids.

Answer 67

copper/silver/gold/platinum

Question 68

68. What products are formed when zinc is added to copper sulfate solution?

Answer 68

zinc sulfate and copper

Question 69

69. What type of reaction takes place when zinc is added to copper sulfate solution?

Answer 69

displacement

Question 70

70. Magnesium reacts with chromium nitrate solution to form magnesium nitrate and chromium. Which metal is more reactive?

Answer 70

magnesium

Question 71

71. Name a metal that reacts vigorously with cold water.

Answer 71

potassium/sodium/rubidium/caesium/lithium/calcium

Question 72

72. What gas is produced when a metal reacts with water?

Answer 72

hydrogen

Question 73

73. How do you test for the gas produced in question 2?

Answer 73

It pops a lighted splint.

Question 74

74. What type of solution is formed when a metal reacts with water - acidic, alkaline or neutral?

Answer 74

alkaline

Question 75

75. What salt is formed when zinc reacts with hydrochloric acid?

Answer 75

zinc chloride

Question 76

76. Complete the word equation, magnesium + copper sulfate makes ...

Answer 76

copper + magnesium sulfate

Question 77

77. What type of ions are formed from metal atoms when they react with acids?

Answer 77

cations/positive ions

Question 78

78. What type of reaction takes place when a substance loses oxygen?

Answer 78

reduction

Question 79

79. Name a metal that occurs uncombined in the Earths crust.

Answer 79

gold/silver/platinum

Question 80

80. Name a metal that could be extracted from its metal oxide by heating with carbon.

Answer 80

zinc/iron/copper

Question 81

81. Name a metal that occurs uncombined in the Earths crust.

Answer 81

gold/silver/platinum

Question 82

82. Name a metal, other than iron, that could be extracted from its metal oxide by heating with carbon.

Answer 82

zinc/copper

Question 83

83. What compound of carbon is formed when it is heated with copper oxide?

Answer 83

carbon dioxide/carbon monoxide

Question 84

84. Why is electrolysis not used to extract iron from iron oxide?

Answer 84

too expensive/too much energy needed

Question 85

85. Why is aluminium not extracted by heating aluminium oxide with carbon?

Answer 85

aluminium is more reactive than carbon/carbon is not reactive enough to remove the oxygen

Question 86

86. What is the aluminium oxide dissolved in to form the electrolyte for electrolysis?

Answer 86

molten cryolite

Question 87

87. What are the electrodes made from?

Answer 87

carbon/graphite

Question 88

88. At which electrode is the aluminium produced?

Answer 88

cathode/negative electrode

Question 89

89. What type of reaction takes place when a metal is extracted from its ore?

Answer 89

reduction/redox

Question 90

90. What type of reaction takes place when a metal corrodes?

Answer 90

oxidation/redox

Question 91

91. What is the definition of oxidation, in terms of oxygen?

Answer 91

gain of oxygen

Question 92

92. H What is the definition of oxidation, in terms of electrons?

Answer 92

loss of electrons

Question 93

93. What type of reaction takes place when metals are extracted from their ores?

Answer 93

reduction/redox

Question 94

94. What is the specific name for the corrosion of iron?

Answer 94

rusting

Question 95

95. Which of these metals will corrode most quickly - iron, sodium, copper?

Answer 95

sodium

Question 96

96. Why does sodium corrode most quickly.

Answer 96

most reactive metal corrodes most quickly

Question 97

97. Which substance has been oxidised in this reaction - copper oxide + hydrogen → copper + water?

Answer 97

hydrogen

Question 98

98. Which substance has been reduced in in this reaction - copper oxide + hydrogen → copper + water?

Answer 98

copper oxide

Question 99

99. What name is given to a process that converts an unwanted product into a new, useful product?

Answer 99

recycling

Question 100

100. Name a type of substance that can be recycled.

Answer 100

metal, plastic, paper, cardboard, glass, etc.

Question 101

101. What can happen in a reversible reaction?

Answer 101

the products can reform the reactants

Question 102

102. What does the term equilibrium describe?

Answer 102

a position of balance

Question 103

103. What is the process used to make ammonia?

Answer 103

Haber Process

Question 104

104. What is the molecular formula of ammonia?

Answer 104

NH₃

Question 105

105. What is the balanced symbol equation for making ammonia from Nitrogen (N2) and Hydrogen (H2)

Answer 105

N₂ +3H₂ → 2NH₃

Question 106

106. Where does nitrogen come from for use in the Haber Process?

Answer 106

From the fractional distillation of air

Question 107

107. Where does Hydrogen come from for use in the Haber process?

Answer 107

From methane from crude oil

Question 108

108. What conditions of pressure are required to increase the yield of ammonia in the Haber Process?

Answer 108

High pressure (because there are more molecules on the LHS of the equation)

Question 109

109. The forward reaction is exothermic. What conditions of temperature are required to increase the yield of ammonia in the Haber Process?

Answer 109

Low temperature (The equilibrium will shit to try and produce heat)

Question 110

110. Theoretically, a high yield of ammonia is produce at low temperature and high pressure. Why is this not used in reality?

Answer 110

Low temperatue will result in a slow rate of reaction. High pressures are expensive and dangerous.