A 25.00 mL sample of a solution of Fe2S3 is found to be 85.2 ppm S2-. The atomic mass of Fe is 55.845 g/mol and the atomic mass of S is 32.066 g/mol. The density of the solution is 1.030 g/mL. What is the molarity of S2- in this solution? What is the weight percent of S2- in this solution?

pH of a solution is defined by - log [H+]. If the [H+] is (6.30 ± 0.05) times 10-3 M for a particular solution, what is the pH? If the pH of a solution is 10.398 ± 0.012, what is the [H+]? Please include the absolute uncertainties for both answers.