# A solution is prepared by dissolving 3.5 #g# of #KCl# in water & making the volume of solution to 250 #mL#. What is the millimoles of #KCl# dissolved?

##### 1 Answer

Your solution contains **47 mmoles** of potassium chloride.

#### Explanation:

To calculate how many *milimoles* of potassium chloride you dissolved in solution, all you really need to do is figure out how many *moles* of the salt you used.

A simple conversion factor will then take you from moles to milimoles.

So, use potassium chloride's molar mass to determine how many moles you added.

To convert to milimoles, simply use the fact that one mole contains **1000 milimoles**.

You need to round this off to two sig figs, the number of sig figs you gave for the mass of the salt.

You can go on to calculate the molarity of the solution in *milimolar*, **mM**.

Once again, round this off to two sig figs to get