Question

II) Water Content in Copper Sulfate Crystal using Electrogravimetry In electro gravimetry, the metal that has to be determined is quantitatively coated on the platinum cathode. By the gain in weight of the cathode, the amount of metal in the sample can be calculated. In the present experiment, the determination water content in copper sulfate crystal (CuSO4xH2O) is utilized as an example for the application of electrogravimetry. The possible reactions in the electrode will be: Cathode: Cv+ + 2e → Cu E=0.337 V H + → H2 E =0.000 V Anode : HO → 10. + 2H+ + 2€ E = 1.229 V Procedure: (1) Weigh accurately-1 g of copper sulfate crystal. Dissolve in deionized water and make up to 100.00 mL in a volumetric flask. (2) Pipet 50.00 mL of the solution into the tall 200 ml beaker which acts as a cell for electrolysis. Add 4 drops concentrated H2SO4 and 2 drops concentrated HNO3. 10 (3) Carefully clean the platinum electrodes with distilled water. Rinse in alcohol or acetone, and dry at 110 °C for 2-3 minutes. Weigh the cathode accurately. Do not touch the gauze of the electrodes with your fingers. (4) Clamp the electrodes making sure that the electrodes are well insulated. (5) Put a stirrer into the electrolytic cell and insert the electrodes. Add in distilled water until about two-thirds of the electrodes are immersed. Adjust the stirrer to give a moderate speed of stirring. 6) Electrolyze at 2-4 volts for about 45 minutes. Check for complete deposition of copper by adding distilled water to the solution so that about lem more of the electrodes is covered. Continue the electrolysis for 6 minutes and observe whether any copper has deposited on the freshly immersed portion of the cathode. If it has, continue the electrolysis for 10 more minutes and try again. Otherwise, the electrolysis is complete. (7) Remove the cathode before turning off the current. Rinse well with distilled water, dry for a few minutes by using the hair-blower and weigh it to the nearest 0.1 mg. (8) From your result, calculate the value x in CuSO4xH20. Compare with the literature value and comment on it. Note: Copper depasited on platimum electrodes may be removed by immessing in 6 M HNO3 until the copper is all dissolved. Rinse the electrode several times with distilled water.

Question: Please calculate the 'x' in CuSO₄xH₂O. Compare with the literature value and comment on it.

Answer 1

height of Cuso. Ho & Paber = 1.07367 - Weight of Paper = 0.0002 g - So Weight of (uso. .H₂O = 1:0736-0.0002 = 1.07349 Height & Pt Cathode = 26.16479 Weight of lu deporitted & Pt Cathode : 28-29449 Weight o lu defosihed = 45.2944–26•|(47 - 0012979 - Molecular weight of (u= 63.5 g mol Nof Moles of Cu delocithed - Weight - - 0.297 63.5 0.00204 So No.d Moles of (uso y oxH o = 0.00204 Weight of (usoy, XH,0 = 1007349

0.00204(63.5) +0.00204(96) +0.00204 (18 ve]=400 734 0.00204 (18x) = 0.747 exist Literatur Xalue = 5 it is known to as Cusou .5H₂O Therefore Our on Sample is too hydrated than Pure literature).