39. Solution to Chemistry Problem

6. Determine the zinc content if a sample of the alloy equal to 0.5412 g is dissolved in acid; zinc is precipitated from the solution with sodium hydrogen phosphate in the presence of an ammonia buffer. The precipitate is filtered, washed and dissolved in 20 ml of a 0.1 M sulfuric acid solution, the excess acid is titrated with 15.85 ml of a 0.12 N sodium hydroxide solution using phenolphthalein.