Question

THE EMPIRICAL FORMULA OF SELECTED HYDRATES experiment PROCEDURE THIS EXPERIMENT SHOULD BE DONE IN PAIRS. 1. Available to you should be: a Büchner funnel, a rubber funnel adapter, side-arm filter flask, thick-walled rubber tubing, plastic forceps and a plastic spatula. 2. Before you turn the hotplate on, wipe the hotplate down with a damp paper towel. During this experiment you will be placing filter paper containing products directly onto the surface of the hotplate. As such, you will want to ensure that your hotplates are clean prior to beginning the experiment. 3. Weigh a clean, dry 250-mL beaker on a top loading balance and record its mass in your lab notebook. Tare the balance. Add 0.8 – 0.9 grams of the copper chloride dihydrate to the beaker and record its exact mass. 4. To a 50-mL graduated cylinder add ~20 mL of DI-water from your wash bottle. Add the water to the copper chloride in the 250-mL beaker. Swirl the solution until the entire solid has dissolved. Record the appearance of the solution in your laboratory notebook. 5. Obtain one zinc bar (~1 cm in length) that has a mass between 0.8 and 1.4 grams and record its exact mass along with the appearance of the zinc bar. 6. Place the zinc bar into the copper chloride solution and record your observations. 7. Use the end of the plastic spatula to carefully clear the surface of the zinc bar and circulate the nearby solution without splashing any of your sample out of the beaker. The reaction will take ~15-20 minutes with your intervention, but much longer without intervention. As such, it is important that you continuously scrape the zinc bar with the plastic spatula. The solution color will likely become yellow-green. Continue to continuously scrape the bar for a total of about 25 minutes. 9. Use a wash bottle to moisten the filter papers with a small portion of DI-water. Make sure that the filter flask is securely clamped to the ring stand before you attach the thick-walled rubber tubing to the house vacuum. When connecting tubing to glassware, first wet the glassware surface then, while wearing gloves, gently twist the tubing on. If the two do not seem to mesh easily, stop and ask for assistance. Turn on the house vacuum valve and place your hand over the mouth of the funnel to test the vacuum. If the vacuum is poor, check the following: (1) the filter adapter and tubing are not cracked, (2) there is a good seal at each end of the rubber tube and at the mouth of the filter flask. 10. After the reaction of zinc with copper chloride is complete, carefully remove the zinc bar using the plastic forceps. Use the plastic spatula to remove any copper that may be adhering to the surface of the zinc and transfer it back to the beaker. Use a paper towel to dry the zinc bar. Weigh and record the mass of the unreacted zinc. 11. Using the opposite end of your stirring rod, decant the mixture into the Büchner funnel so that most of the copper particles remain behind in the beaker. This is achieved by holding the spatula vertically, touching the spout of the beaker, and slowly tipping the beaker to allow the solution to drain slowly without disturbing the precipitate. It is usual to have a small amount of copper collecting on the filter paper. The supernatant liquid (also called the filtrate) is collected in the filter flask and contains the chloride ions in the form of zinc chloride solution. Record the appearance of the copper solid and of the filtrate. 12. Use a wash bottle to rinse the copper in the beaker with ~10 mL portions of DI-water, then decant the washings into your Büchner funnel (again, try to leave most copper in the beaker). Place the beaker containing the copper on a hotplate for drying, following the drying The filtrate from the second filtration will contain. Careful! (Select all that apply.) chloride ions silver ions zinc ions nitrate ions

The filtrate from the second filtration will contain. Careful!

(Select all that apply.)

chloride ions
silver ions
zinc ions
nitrate ions

Answer 1

Ans:

This is a redox reaction in which Zinc metal gets oxidised to Zn2+ and Copper ions from Copper(II)chloride gets reduced to Copper (0) metal.Which is precipitated out and removed via filtration of the reaction mass.

CuCl2 + Zn (metal) --> ZnCl2 + Cu (metal) (balanced reaction)

Cu2+ + 2 e- (from zinc) → Cu0 (reduction)

Zn0 - 2 e- (to copper) → Zn2+ (oxidation)

Chloride ions (Cl-) from initial CuCl2 will be the counter ions of Zn2+ now. Copper (0) as metal will preipitate out.

In the above set of reaction as described, there is no Silver or Nitrate salts are used, hence after filtration the

filtrate will contain only Chloride  and Zinc ions in water media.