!Answer!: 0.0152 gram.
(d) The clean electrode weighs 10.9640 grams. Calculate the weight after the copper has been deposited.
!Answer!: 11.6116 grams.
(e) Calculate the grams of (NH_{4}){2}HPO{4} required to precipitate the zinc as ZnNH_{4}PO_{4}.
!Answer!: 0.5705 gram.
(f) Calculate the weight of ignited Zn_{2}P_{2}O_{7}.
!Answer!: 0.6573 gram.
100. If in the analysis of a brass containing 28.00% zinc an error is made in weighing a 2.5 gram portion by which 0.001 gram too much is weighed out, what percentage error in the zinc determination would result? What volume of a solution of sodium hydrogen phosphate, containing 90 grams of Na_{2}HPO_{4}.12H_{2}O per liter, would be required to precipitate the zinc as ZnNH_{4}PO_{4} and what weight of precipitate would be obtained?
!Answers!: (a) 0.04% error; (b) 39.97 cc.; (c) 1.909 grams.
101. A sample of magnesium carbonate, contaminated with SiO_{2} as its only impurity, weighs 0.5000 gram and loses 0.1000 gram on ignition. What volume of disodium phosphate solution (containing 90 grams Na_{2}HPO_{4}.12H_{2}O per liter) will be required to precipitate the magnesium as magnesium ammonium phosphate?