Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Giant ionic structures
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →Explain why giant ionic structures conduct electricity when molten but do not conduct when solid.
Question 12
4 marks · Normal
Answer and see the solution →The table below gives the melting points and ability to conduct electricity in the solid and molten states for some ionic compounds:
Melting points and conductivity of ionic compounds Compound Melting point (°C) Conducts electricity when solid? Conducts electricity when molten? Sodium chloride 801 No Yes Magnesium oxide 2852 No Yes Potassium bromide 734 No Yes (a)[1 mark]Which compound has the highest melting point?
(b)[2 marks]Suggest a reason why all three compounds do not conduct when solid.
(c)[1 mark]What allows these compounds to conduct when molten?
Question 13
1 mark · Normal
Answer and check →Which property best explains why potassium chloride has a high melting point?
- A.It consists of molecules joined by covalent bonds.
- B.Its ions are arranged in layers that slide past each other.
- C.It is made of positive and negative ions held by strong electrostatic forces.
- D.It has delocalised electrons that conduct electricity.
Question 14
2 marks · Normal
Answer and see the solution →Describe the structure of a giant ionic compound and explain how this structure is linked to its melting point.
Question 15
4 marks · Normal
Answer and see the solution →Calcium chloride is an ionic compound with the formula CaCl_2.
(a)[1 mark]Name the ions present in calcium chloride.
(b)[2 marks]Explain why calcium chloride is soluble in water but does not conduct electricity when solid.
(c)[1 mark]What must happen for solid calcium chloride to conduct electricity?
Question 16
3 marks · Normal
Answer and see the solution →A student is comparing the melting points and electrical conductivity of two compounds: sodium chloride (NaCl) and magnesium oxide (MgO).
(a)[1 mark]Sodium chloride melts at around 801°C, while magnesium oxide melts at about 2852°C. Calculate the difference in melting points between these two ionic compounds.
(b)[2 marks]Explain, using the structure and bonding in giant ionic lattice structures, why magnesium oxide has a much higher melting point than sodium chloride.
Question 17
2 marks · Hard
Answer and see the solution →Lead(II) bromide (PbBr_2) is an example of a giant ionic compound. Explain why solid lead(II) bromide does not conduct electricity, but molten lead(II) bromide does.
Question 18
5 marks · Hard
Answer and see the solution →Sodium sulfide (Na_2S) and aluminium oxide (Al_2O_3) are both giant ionic compounds.
(a)[2 marks]Describe the arrangement of ions in the lattice of a giant ionic compound.
(b)[3 marks]Explain, using your knowledge of structure, why the melting point of aluminium oxide is much higher than that of sodium sulfide.
Question 19
2 marks · Hard
Answer and see the solution →State and explain whether potassium iodide (KI) has a high or low melting point. Refer to its structure in your answer.