4. Give two reasons why graphite (carbon) electrodes are used in electrolysis.

5. You have 2 compounds called X and Y.
X melts at 1200 degrees C and is soluble in water.
Y melts at 156 degrees C and is insoluble in water.

Draw 2 diagrams to show how you could prove which of these substances is an electrolyte or a non- electrolyte.

How would you know which was an electrolyte and which was not.

What must a substance contain to be an electrolyte?

4. Graphite is a good electrical conductor and does not react chemically with most electrolytes.

5. (a) Ionic solids have high melting points and many of them have high solubility in water. (b) Molecular solids have low melting points and many of them do not dissolve in water.

4. Graphite (carbon) electrodes are used in electrolysis for two main reasons:

a) Conductivity: Graphite electrodes are excellent conductors of electricity. When an electric current is passed through the electrolyte solution, ions in the solution migrate towards the electrodes. Graphite electrodes allow the flow of electrons, facilitating the movement of ions, which is crucial for the electrolysis process.

b) Chemical Stability: Graphite electrodes are chemically stable and do not react with most electrolytes. This property is crucial to ensure that the electrodes do not undergo any unwanted reactions or dissolve during electrolysis. It allows for a continuous and efficient electrolysis process.

5. To determine whether substance X or Y is an electrolyte or a non-electrolyte, you can perform an electrolysis experiment using a setup called an electrolytic cell. Here are two diagrams showing the experimental setup for each substance:

Diagram for Substance X (possible electrolyte):
+----------------------+
| Electrolysis |
| Cell for X |
| |
| X (molten) or |
| dissolved in H2O |
| |
| Electrodes: |
| Graphite (C) |
| |
| Power Source |
+----------------------+

Diagram for Substance Y (possible non-electrolyte):
+----------------------+
| Electrolysis |
| Cell for Y |
| |
| Y (molten) |
| |
| Electrodes: |
| Graphite (C) |
| |
| Power Source |
+----------------------+

In both cases, the power source provides an electric current that passes through the electrolytic cell, causing the electrodes to react with the substances being tested.

To determine which substance is an electrolyte and which is not, you would observe the following:

- For Substance X (possible electrolyte):
If X is an electrolyte, when the electric current is passed through the cell, X will conduct electricity and undergo chemical reactions at the electrodes. This may lead to the generation of gases or the deposition of substances on the electrodes.

- For Substance Y (possible non-electrolyte):
If Y is a non-electrolyte, it will not conduct electricity, and you would not observe any chemical reactions or the generation of gases at the electrodes. The substance will remain stable throughout the electricity passing through the cell.

6. For a substance to be an electrolyte, it must contain ions. In other words, it needs to have dissociated into positively and negatively charged particles called ions when dissolved or molten in a solvent. These ions can move freely in the solution or melt, enabling the conduction of electricity. The presence of ions allows an electrolyte to form an electrically conductive path, making it responsive to an applied electric current.