What is Dilution, stock solution, dilution factor?

Example 26.14 (A tenfold dilution)

A stock solution of copper sulfate has $c_0 = 0.10\,\mathrm{mol}/\mathrm{L}$; $100.0\,\mathrm{mL}$ at $c_1 = 0.010\,\mathrm{mol}/\mathrm{L}$ are needed. The dilution factor is $F = 0.10 / 0.010 = 10$, so $V_0 = 100.0\,\mathrm{mL} / 10 = 10.0\,\mathrm{mL}$: a $10.0\,\mathrm{mL}$ pipette and a $100.0\,\mathrm{mL}$ flask.

Example 26.16 (A blue scale)

From a stock solution of copper sulfate at $0.20\,\mathrm{mol}/\mathrm{L}$, six standards are prepared at 0.02, 0.04, 0.06, 0.08, 0.10 and $0.12\,\mathrm{mol}/\mathrm{L}$, each in identical tubes filled to the same height. A solution of unknown concentration, in the same kind of tube, looks darker than the $0.06\,\mathrm{mol}/\mathrm{L}$ tube and paler than the $0.08\,\mathrm{mol}/\mathrm{L}$ one: its concentration lies between the two, about $0.07\,\mathrm{mol}/\mathrm{L}$.