Properties of ionic compoundsIB MYP Chemistry: Mind map

Exam questions on Properties of ionic compounds

1. A student in Cairo heats a few crystals of sodium chloride in a crucible over a Bunsen burner. The crystals do not melt, even though the flame is very hot. A furnace is needed to melt sodium chloride, at 801 °C.
   Explain why sodium chloride has such a high melting point.2 marks
2. A teacher in Auckland gives students a white solid labelled X. They find that X does not conduct electricity when solid, melts only above 700 °C, and conducts electricity well when molten. X also dissolves in water, and the solution conducts electricity.
   Explain why X does not conduct electricity when solid but does when molten.2 marks
3. A student in Kuala Lumpur investigates how well salt solutions conduct electricity. She dissolves 0 g, 2 g, 4 g, 6 g and 8 g of sodium chloride in separate 100 cm³ portions of distilled water and measures the current in each solution, using the same circuit and electrodes every time. The ammeter readings were 0.00 A, 0.18 A, 0.35 A, 0.52 A and 0.69 A. She predicted that the more sodium chloride dissolved, the greater the current.
   Describe the trend in her results and explain it.3 marks