What would happen with non-electrolytes?
4 marks · NormalThe table below shows results from an experiment where a student measured the volume of oxygen gas produces at the anode when different substances are electrolysed:
| Substance (aq) | Bulb lights? | Volume of O2 at anode (cm³) |
|---|---|---|
| Sodium sulfate | Yes | 18.5 |
| Copper(II) sulfate | Yes | 17.8 |
| Sugar | No | 0 |
| Ethanol | No | 0 |
Identify which substances are electrolytes and which are non-electrolytes. Explain your choices.
State what this experiment shows about the type of bonding in sugar and ethanol.
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) Sodium sulfate and copper(II) sulfate are electrolytes; sugar and ethanol are non-electrolytes. Electrolytes conduct electricity (bulb lights and gas formed); non-electrolytes do not.
(b) Sugar and ethanol are covalent compounds; they do not contain ions and do not conduct electricity.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly identifies sodium sulfate and copper(II) sulfate as electrolytes.
B2 (a) · 1 mark · Correctly explains that non-electrolytes (sugar, ethanol) do not conduct and bulb does not light.
B3 (b) · 1 mark · States that sugar and ethanol are covalent compounds/non-electrolytes.
B4 (b) · 1 mark · Explains sugar and ethanol do not conduct because they do not form ions in solution.
Worked solution
a) Sodium sulfate and copper(II) sulfate are electrolytes because the bulb lights up and oxygen gas is produced at the anode for both—they contain ions that move. Sugar and ethanol are non-electrolytes, since the bulb does not light and no gas is produced; they do not conduct electricity.
b) The experiment shows that sugar and ethanol are covalent compounds, as they do not conduct electricity and therefore do not produce ions in solution.