The law of Definite CompositionHoa ChungChemistry 1A Spring 2016 February 25, 2016Objective/Purpose1.To prepare the compound “copper sulfide”.2.To determine the empirical formula of “copper sulfide”.TheoreticalThe metal, copper, and the non-metal, sulfur (in the vapor state), will be chemicallycombined to form a compound, copper sulfide, which will have completely different propertiesthan the copper or the sulfur.Synthesis reaction: metal + nonmetalcompoundCopper + sulfur (in vapor state)copper sulfideBy using a predetermined amount of copper and determining the mass of copper sulfideproduced, it is possible to calculate the percentage by mass of each element in the compound.From this information the chemical formula of the compound can be determined.Determination of % composition of elements by experimentIn general:% element =masselementmasscompoundx100Assuming the Law of conservation of mass is true, thenMass metal + mass nonmetal = mass compoundAverage=x1+…+x1313Deviation=δ1
