A3.0% (m/v) potassium chloride solution has a volume of 25.0 ml. how many moles of potassium chloride are in the sample? i would answer this. but my teacher skimmed through this section of the text. and he won’t me with it. i just know that m/v is g/ml and mls should cancel out right? and moles come from mole/l. i am not sure what to do though.

Using your knowledge of m/v = g/mL, you can start by putting that in the equation as:



And you know that the volume is 25 mL. So you could put this into the equation as:



And you also know that the molar mass of KCl is 74.55g (K = 39.1 g/mol and Cl = 35.45 g/mol. Add them together to get 74.55g/mol).

We can then put this in the equation as:



Then, we can mulitply them all together:



And now we know that there are 0.01 moles of KCl in the sample.