I am researching how to Determination of Vitamin C Concentration by Titration for my science fair project and it says

Titrate the sample with $0.005~\mathrm{mol~L^{−1}}$ iodine solution. The endpoint of the titration is identified as the first permanent trace of a dark blue-black color due to the starch-iodine complex.

Does this mean to add iodine until it turns dark blue-black color?

What does $\mathrm{mol ~L^{−1}}$ mean?


1 Answer 1


The units are mole per liter. $\mathrm{mol \times L^{-1}}$ is more conveniently written $\mathrm{mol/L}$. This set of units is referred to as molarity, and is a common measure of concentration for a solute dissolved in a solvent. The solute may be a solid (ionic or covalent), a gas or a liquid, but is commonly a solid. The solvent may be a gas or liquid, but is commonly a liquid. Together, the solute and the solvent form a solution.

Specifically, molarity is defined as

$$\text{Molarity} = \frac{\text{mol of solute}}{\text{L of solution}}$$

Note that the volume is of the total solution, not simply the solvent. In a dilute aqueous solution (a small amount of something dissolved in water), we may approximate the solution volume as simply the volume of solvent.


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