Topic 5 Mass calculations, electrolysis, 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

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

Answer 4

(H = 2, S = 1, O = 4)

Question 5

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 5

58.5

Question 6

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

Answer 6

2

Question 7

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 7

18

Question 8

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 8

44

Question 9

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

Answer 9

CH₂

Question 10

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

Answer 10

C₃H₈

Question 11

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

Answer 11

gas/carbon dioxide escaped

Question 12

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

Answer 12

combines with oxygen

Question 13

23. How many cm³ are there in 1 dm³?

Answer 13

1000

Question 14

26. 100 cm³ of a solution contains 1.5 g of salt. What is the concentration of the salt solution in g d³?

Answer 14

15

Question 15

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

Answer 15

ion

Question 16

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

Answer 16

positive

Question 17

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

Answer 17

negative

Question 18

34. What is another name for a positive ion?

Answer 18

cation

Question 19

35. What is another name for a negative ion?

Answer 19

anion

Question 20

36. What is the symbol for a sodium ion?

Answer 20

Na⁺

Question 21

37. What is the symbol for a magnesium ion?

Answer 21

Mg²⁺

Question 22

38. What is the symbol for a chloride ion?

Answer 22

Cl^{<span>-</span>}

Question 23

40. In what states do ionic compounds conduct electricity?

Answer 23

when molten or dissolved in water

Question 24

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

Answer 24

anode

Question 25

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

Answer 25

anions / negative ions

Question 26

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

Answer 26

cathode

Question 27

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

Answer 27

cations / positive ions

Question 28

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

Answer 28

lead

Question 29

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

Answer 29

hydrogen

Question 30

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

Answer 30

effervescence/fizzing/bubbles/magnesium disappears

Question 31

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

Answer 31

copper/silver/gold/platinum

Question 32

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

Answer 32

zinc sulfate and copper

Question 33

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

Answer 33

displacement

Question 34

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

Answer 34

potassium/sodium/rubidium/caesium/lithium/calcium

Question 35

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

Answer 35

hydrogen

Question 36

63. How do you test for Hydrogen?

Answer 36

It pops a lighted splint.

Question 37

66. Complete the word equation, magnesium + copper sulfate makes …

Answer 37

copper + magnesium sulfate

Question 38

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

Answer 38

reduction

Question 39

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

Answer 39

gold/silver/platinum

Question 40

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

Answer 40

zinc/iron/copper

Question 41

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

Answer 41

zinc/copper

Question 42

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

Answer 42

reduction/redox

Question 43

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

Answer 43

oxidation/redox

Question 44

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

Answer 44

gain of oxygen

Question 45

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

Answer 45

rusting

Question 46

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

Answer 46

sodium

Question 47

86. Why does sodium corrode most quickly.

Answer 47

most reactive metal corrodes most quickly

Question 48

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

Answer 48

recycling

Question 49

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

Answer 49

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

Question 50

99. What can happen in a reversible reaction?

Answer 50

the products can reform the reactants

Question 51

100. What does the term equilibrium describe?

Answer 51

a position of balance