# I need to make a "6 M" solution of "KI" in "50.00 mL". I tried to dump "49.8 g" of "KI" into "50.00 mL" of water in a volumetric flask, but I can't dissolve it. What can I do? Also, is it okay that the volume reading is above the mark??

Feb 14, 2016

What you could have done was put a little bit in at a time into a flask that already contains some amount of water, dissolving it a bit at a time. It's easier to swish around when there isn't a lot of solid in the flask.

Then when all $\text{49.8 g}$ dissolves, as it should (its solubility is $\text{70 g/50 mL}$ in water at ${20}^{\circ} \text{C}$), add more water until you reach exactly $\text{50.00 mL}$.

Granted, that amount of solid will displace the water quite a bit, so ask your instructor what he/she is looking for.

Alternatively, if you have a sonicator, that should help dissolve it by sending vibrations through the flask.

Or, heat it up in a capped flask on a hot plate to, say, ${60}^{\circ} \text{C}$ (${140}^{\circ} \text{F}$) while using a magnetic stir bar, and then let it cool down. It'll speed up the solvation, but capping it will prevent a lot of vapors escaping and dehydrating the solution.