The electrical conductivity of ionic substances
3 marks · EasyThe table below shows whether four substances conduct electricity in different states.
| Substance | Solid | Molten | Aqueous |
|---|---|---|---|
| Calcium Bromide | No | Yes | Yes |
| Iron(II) chloride | No | Yes | Yes |
| Sodium phosphate | No | Yes | Yes |
| Iodine | No | No | No |
From the substances in the table, identify all that are ionic compounds.
What property do these ionic compounds share in relation to conducting electricity?
Explain how the table helped you determine which substances are ionic.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Calcium bromide, iron(II) chloride, sodium phosphate
(b) They all conduct electricity when molten or aqueous, but not when solid.
(c) Only substances that do not conduct when solid but do conduct when molten or dissolved are ionic.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies all three ionic compounds.
B1 (b) · 1 mark · States correct property in terms of electrical conduction in different states.
B1 (c) · 1 mark · Explains identification was based on conduction pattern (no when solid, yes when molten/aqueous).
Worked solution
a. Calcium bromide, iron(II) chloride, sodium phosphate are ionic compounds. b. They conduct electricity when molten or aqueous, but not when solid. c. I identified them as ionic because only ionic compounds show this pattern of conduction: not conducting as solids, but conducting when molten and in solution.