1. The problem statement, all variables and given/known data Identify the bottles 2. Relevant equations 3. The attempt at a solution Bottle 1 is lead nitrate as lead is the only metal that will form a precipitate with the other anions. Bottle 3+4 = copper sulfate + sodium carbonate -- because it produces blue precipitate Bottle 2+3 = hydrochloric acid + sodium carbonate -- as acid + metal = salt + hydrogen gas. This means sodium carbonate is bottle 3, hydrochloric acid is bottle 2, and copper sulfate is bottle 4. Can someone check this? If this is correct, out of interest, why doesn't hydrogen gas evolve when HCl is added to lead nitrate and copper(II) sulfate? Cheers!