I'm conducting an experiment using iron(III) chloride in aqueous solution, but am also aware that it's usually a solid.
How is iron(III) chloride experimentally converted to a solution?
And can you please explain how the conversion happens and its mechanism.
You can prepare a solution of $\ce{FeCl3}$ by dissolving the appropriate amount in water.
Let's say you want a $0.1 \text{ M}$ solution of $\ce{FeCl3}$. You would do this by dissolving 0.1 mole of $\ce{FeCl3}$ in 1 liter of water.
$$0.1000 \text{ mol} \times \dfrac{162.2\text{ g}}{1\text{ mol}}=16.22 \text{ g}$$
You would need to dissolve 16.22 g of $\ce{FeCl3}$ in enough water to make 1 liter of solution.
This solution is not stable over time. $\ce{FeCl3}$ hydrolyzes in water. See my answer to this question. The hydrolysis can be slowed/reversed by adding $\ce{HCl}$. Since solutions of $\ce{FeCl3}$ are already acidic, there is no harm usually in adding more acid. For this 0.1 molar solution, you might choose to dissolve 16.22 g of $\ce{FeCl3}$ in enough 0.1 M HCl to make one liter of solution.
How is iron(III) chloride experimentally converted to a solution?
Iron (III) chloride dissolves in water via acid base chemistry. Iron is the Lewis acid in this case (electron pair acceptor) and water is the Lewis base (electron pair donor). Iron (III) becomes solvated with six water molecules, forming an octahedral complex via the water's oxygen atoms. This pulls electron density away from the water's hydrogens, making them available to be pulled off in solution by other water molecules, a process called hydrolization. Thus the solution becomes more acidic; as iron (III) becomes solvated it increases the concentration of H3O+ in solution.
