A student wants to electroplate copper onto a negative electrode using the electrolysis of copper(II) sulfate solution.
Some possible steps they can use in the electrolysis experiment are listed.
- Connect the electrodes to the DC power supply.
- Clean the negative electrode with emery paper.
- Evaporate the copper(II) sulfate solution to dryness.
- Record the initial mass of the clean, dry negative electrode.
- Pour the copper(II) sulfate solution into the beaker.
- Heat the solid copper(II) sulfate until it melts.
Put the four steps that the student should use in the correct order.
□→□→□→□ \Box \rightarrow \Box \rightarrow \Box \rightarrow \Box □→□→□→□Sulfur is in Period 3 and Group 6 of the Periodic Table.
Which statements about sulfur are correct?
Tick (✓\checkmark✓) two boxes.
- Sulfur forms positive ions.
- Sulfur has 6 electrons in its outer shell.
- Sulfur has 6 electron shells.
- Sulfur has 16 outer electrons.
- Sulfur is a metal.
- Sulfur is a non-metal.
The student sets up another electrolysis experiment using zinc bromide solution, ZnBr2\text{ZnBr}_2ZnBr2.
The table shows their results.
| Experiment | Mass of zinc made (mg) | Volume of bromine gas made (cm3\text{cm}^3cm3) |
|---|---|---|
| 1 | 6.5 | 2.4 |
| 2 | 13.0 | 4.8 |
| 3 | 19.5 | 7.2 |
| 4 | 26.0 | |
| 5 | 32.5 | 12.0 |
Estimate how much bromine gas will be made in experiment 4.
Volume of bromine gas made = ........................................................... cm3\text{cm}^3cm3
Describe the relationship between the mass of zinc made and the volume of bromine gas made.
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Zinc bromide solution is an electrolyte.
What type of compound is an electrolyte?
Tick (✓\checkmark✓) one box.
- Covalent
- Giant Molecular
- Ionic
Another student repeats the electrolysis of copper(II) sulfate solution to determine the mass of copper deposited on the negative electrode.
They record the mass of the negative electrode at the start of the experiment.
At the end of the experiment, they remove the negative electrode from the copper(II) sulfate solution and record the mass immediately as shown in the diagram.
They notice that the mass is higher than they expect.
Suggest two changes the student could make to get a more accurate mass.
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