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QUESTION 6 Two crystalline solids, P and Q have melting points of 710oC and 723oC respectively. At 700oC, substance P conducts electricity but Q does not. At 750oC, both P and Q conduct electricity. 6.1 What can be deduced from the melting points about the relative magnitude of the forces between the particles in P and Q? (2) 6.2 Explain the difference observed in electrical conductivity between P and Q. (4) 6.3 You are told that one of the solids is Barium and the other is potassium iodide. Which is P and which is Q? (2) 6.4 What is the difference between covalent and ionic bonding? (2) 6.5 Name 5 different types of intermolecular forces (5)           [15]

QUESTION 2 Water has a high heat of vaporisation value of 40,7 kJ.mol-1. 2.1 Identify the attribute of water causing this high heat of vaporisation. (1) 2.2 Discuss the advantage of the resistance mentioned in QUESTION 2.1  for our planet and all living organisms. (3) A water molecule is polar while a carbon dioxide molecule is non- polar. 2.3 What is the difference between a polar and a non- polar molecule? (2) 2.4 What is the name of the shape given to the water molecule? (1) 2.5 Use electronegativity difference to determine the type of bond present in the carbon dioxide molecule. (2) 2.6 What is the easiest way to increase the amount of kinetic energy in a system? (2) 2.7 How does the density of a solid compare to the density of a liquid? Explain your answer in terms of intermolecular forces. (3) 2.8 What are meant by the terms ‘thermal expansion’ and ‘thermal conductivity’? (4) 2.9 What happens to the density of liquid water as the temperature rises? Briefly explain your answer. (3)           [21]

1.10 The mass (in grams) of 7,25 dm3 of O2 gas at STP is:   (2)

1.7 Sodium chloride (NaCl) is a solid which is soluble in water. Which one of the following describes the intermolecular forces that exist between sodium chloride and water in solution?         (2)

1.6 The bond in the H2O molecule is described as polar covalent because:   (2)

QUESTION 3 Consider a hydronium ion (H3O+). 3.1 Draw the Lewis structure of H3O+. (3) 3.2 Identify the shape of H3O+. (1) 3.3 Use the VSEPR to explain the shape mentioned in QUESTION 3.2 (2) 3.4 Explain what is meant by a dative covalent bond. (2)           [8]

1.2 Choose the molecule with a trigonal pyramidal shape: (2)

1.3 Which of the following are the types of forces of attraction between non-polar molecules?   (2)

TOTAL FOR PAPER: [125]

1.8 Consider the balanced chemical equation: 2H2(g) + O2(g)