Describe a test to identify lithium ions in the solution. State the expected observation.

Describe a test to identify iodide ions in the solution. State the expected observation.

The student determined the concentration of lithium iodide in the salt solution using the following method:

1. Weigh an empty evaporating basin.
2. Transfer $50.0{cm}^3$ of the salt solution into the basin.
3. Heat the evaporating basin and its contents.
4. Weigh the evaporating basin and its contents.
5. Repeat the heating and weighing steps until there is no further change in mass.
6. Repeat steps 1 to 5 with three more samples.

Explain why the student heated the evaporating basin and its contents until a constant mass was achieved.

How did the student determine the mass of the dry lithium iodide remaining after completing step 5?

Select one option:

• Option A: $Mass\; of50.0{cm}^{3}of\; salt\; solution-mass\; of\; empty\; evaporating\; basin$
• Option B: $Mass\; of\; evaporating\; basin\; and\; dry\; contents-mass\; of\; empty\; evaporating\; basin$
• Option C: $Mass\; of\; empty\; evaporating\; basin-mass\; of\; evaporating\; basin\; and\; dry\; contents$
• Option D: $Mass\; of\; evaporating\; basin\; and\; dry\; contents+mass\; of\; empty\; evaporating\; basin$

The student calculated the concentration of lithium iodide in the salt solution for each trial. Table 1 shows these results:

The percentage by mass of lithium ions in lithium iodide is $5.16\%$.

Calculate the mean concentration of lithium ions in the salt solution. Give your answer to 3 significant figures.