OK. There may be formulas in use for every application, but not everyone knows them all. It may be hard to find the formula you want, on the webpage you want, the the situation you have, each time.

However, understanding the underlying concepts, and using them, lets you determine the formula for every situation. That's a smarter way to work. That's what most people want to do.

I don't understand your jargon, and the way its calculated:

so the concentration of molecule A is 0.5% mol.

This is calculated by (number of molecules of A / total number of molecules) x 100

mol%? What's that? Mole fraction? Molar? Molar %? And your calculation doesn't make sense to me either.

I have looked all over the interent and nothing has helped, the only solution from my research seems to be to convert mol% to mol (so it would be 0.005?) and then multiply that by the Mw, then divide by 10 (not sure why, something to do with units).

Here's something you can do. Write the units, on paper, for each part of the conversion. You can then cancel units, striking through, on paper. So you can understand what that '10' means, or even if its applicable.

Come on, this is simple. Suppose you have 1 mole of molecules in total. How many moles of A? How many moles of water? What is the mass of A? The mass of water?

I’m not really sure what you mean. How can I calculate moles without a volume? I am ideally just looking for a formula or a guide that I can apply to my problem.

If you're in the mood to try this, pick a volume at random, like

**mjc123:** picked a mass at random. And see what you get. Select the volume of 100 ml, that way, percentages are easy to find. Also try 10 ml, and 1 mL. Those are powers of 100, and easily convertible.

This is how we learn these concepts. If you need to quickly make a solution to do some work this may seem tedious. But you haven't given us enough context to help in that case.