mass of crucible- 10.3714gmass of crucible and hydrated sample- 11.4552gmass of hydrated sample 1.0838gmass of crucible and dehydrated sample- 11.217gmass of dehydrated sample- .8459gmass of filter paper- .1999gmass of filter paper and copper- .6678gmass of copper- ?no. moles of copper- ?mass of water evolved- ?no. moles of water- ?mass of chlorine in sample (by difference)- ?no. moles of chlorine- ?mole ratio, chlorine:copper in sample- ?mole ratio, water:copper in hydrated sample- ?formula of dehydrated sample (round to nearest integer- ?formula of hydrated sample- ?I'm somewhat confused and I wanted my answers double checked. I ended up getting no. moles of chlorine- .0107 mol Cl and .0074 mol Copper as well as .0132 mol water. My ratios are iffy, as well. I'd appreciate any help !
Practically speaking, there is only one compound of copper and chlorine that it could be: CuCl2 CuCl2?nH2O ........ 1.0838g CuCl2 (anhydr) .... 0.8459g H2O ..................... 0.2379g 0.8459g CuCl2 x (1 mol CuCl2 / 134.5g CuCl2) = 0.00629 mol CuCl2 / 0.00629 = 1 0.2379g H2O x (1 mol H2O / 18.0g H2O) = 0.0132 mol H2O / 0.00629 = 2.1 Formula of hydrate: CuCl2?2H2O ---------------------------------------... Your moles give these results, and are very iffy 0.0074 mol Cu / 0.0074 = 1 0.0107 mol Cl / 0.0074 = 1.45 0.0132 mol H2O / 0.0074 = 1.78 My calculations .... close enuff Mass of copper = 0.4679g .... 0.00736 mol Cu Mass of chlorine = 0.378g ..... 0.106 mol Cl And how did you arrive at the mass of copper? Perhaps something like this: Dissolve the anhydrous CuClx in water and then reduce the copper ions with an iron nail and knock all the copper loose and collect it in a weighed filter paper, and then allow it to dry. I have no doubt in the world that your sample was originally CuCl2?2H2O. With an original sample mass of 1.0838g you should have found .... 1.0838g CuCl2?2H2O x (1 mol / 170.5g) = 0.00636 mol CuCl2?2H2O Cu = 0.00636 mol Cl = 0.0127 mol H2O = 0.0127 mol
Since there are twice as many chlorides as cobalt (.0084 vs .0042) the empirical formula for the anhydrous compound is CoCl? Likewise, since there are six times as many water as cobalt moles, (.0255 vs .0042) that ratio is 6:1 So you have Cobalt II Chloride Hexahydrate, or CoCl? ? 6H?O Copper 1 Chloride would be CuCl Copper II Chloride would be CuCl?. So (x, y) would be (1, 1) or (1, 2)
