How to make 0.6M of phosphoric acid from 4.1Moles ?
First, it helps to write ‘moles’ with a small ‘m’ to help you separate moles from Molarity. Then, start with the fact that 1 mole of a material is the MW or FW in grams. 1 mole of a material that has a molecular weight of 96.22, for instance would be 96.22 grams. Now a 1 Molar solution would be 1 mole of that material dissolved in 1 Liter of total solution. Our example material would therefore have a 1M solution be made up of 96.22 grams in 1 Liter of solution. The fact that your starting solution is 85% H3PO4 adds to the fun – try working out what the theoretical Molarity of 100% phosphoric acid would be and adjust from there. Oh, and just to confuse the issue further, %ages in chemistry are usually defined as w/v or v/v in these circumstances, meaning X g/100 mL (w/v) or X mL/100 mL (v/v). Take it step by step and good luck!
