In an attempt to make this a better learning experience, here is the best conclusion I could come up with. Make yours the same.

Molarity is the measurement of solution concentration as expressed mathematically as moles of solute divided by liters of solution. No other units are allowed into the formula. Not grams, not mL. Only moles and only liters.

Percent comp by mass is old school by now. It’s the proportion that part of something makes in regard to the whole. The formula is

Parts per million is used to measure the concentration of solutions that are very, very dilute. One part in a million is as small as an inch is in 16 MILES. The formula is

The dilution formula is used to figure out how much stock solution you need to make a new solution from the existing one. The new solution has to be less concentrated, or more dilute, than the original. The formula is

M_{1}V_{1} = M_{2}V_{2 }

Which stands for the molarity of the stock solution times the volume of the stock (which is the unknown always)

equal to the molarity of the new solution that you want times the volume of the new solution that you want.

Volume can be in any units, as long as they match on both sides of the equal sign. Liters or mL are okay.

Then make up one problem, a PPM or a MOLARITY math problem, which you must solve. It has to have 4 SF, so you have to think and be careful.