1. The problem statement, all variables and given/known data Here is two similar questions but which I got a different answer to the back of the book 1. You are to prepare 50ml of 2M sulfuric acid, which is to be added to a sample of white wine to make the sulfur dioxide preservative in the wine available in solution, so that its concentration can be determined. What volume of concentrated (18M) acid will you prepare? 2. A factory discharged 15ML of a liquid waste containing 12ppm (v/v) of a highly toxix compound into a pond. Before it was added, this pond already contained 920ML of wastewater in which this compound was present at a concentration of 0.23ppm (v/v). What was the new concentration of this compound in this pond? 2. Relevant equations conversions 3. The attempt at a solution Q1. 2 moles/litre, 50ml => 0.1moles 18moles/litre. Need 0.1moles so 0.1/18=0.0056L=5.56ml but answers suggest 16ml Q2. ppm (v/v) => 1g/10^6g = 1g/1000kg 1L=1kg assuming solvent is water 15ML @ 12ppm => 15*10^6 kg @ 12g/1000kg => 15*10^3 * 12g grams of solute or 180kg of solute 920ML @ 0.23ppm => 920*10^6 kg @ 0.23g/1000kg => 920*10^3 * 0.23g or 211.6kg of solute Hence total solute is 391.6kg. Total solution is 935ML. So a new total concentration of 391.6kg/(935*10^6kg) * 10^6g = 0.42g/10^6g or 0.42ppm. But the answers suggest 0.49ppm. Who is wrong?