Asample of copper wire with a mass of 1.659 g is heated with excess powdered sulfur until the copper has combined with the sulfur, and all the extra sulfur has been burned off. the final product (a sulfide of copper ) has a mass of 2.080 g. calculate the empirical formula of the product, and name it.

Achemistry student needs to standardize a fresh solution of sodium hydroxide. he carefully weighs out of oxalic acid , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in of distilled water. the student then titrates the oxalic acid solution with his sodium hydroxide solution. when the titration reaches the equivalence point, the student finds he has used of sodium hydroxide solution.calculate the molarity of the student's sodium hydroxide solution. be sure your answer has the correct number of significant digits.