3. Copper (I) sulfide is insoluble in aqueous ammonia, while copper 0) sulfide d

Question

3. Copper (I) sulfide is insoluble in aqueous ammonia, while copper 0) sulfide dissolves to give a blue solution. Using the chemical fume hood,Group3 heated a small wire coil copper covered with sufficient powdered sulfur of inside a crucible. They continued heating until no more smoking is observed. A dull black brittle substance was left in the crucible. To a sample of the brittle substance inside a test tube, Group 3 added 2 ml of 6MNHdoil. The mixture remained unchanged after heating the test tube gently. Based on this observation, complete and balance the equation Why is it necessary to perform this experiment in the fume hood? Atest tube containing 3 ml of (PboNO) solution was added with 3 mL on and a white precipitate was formed. (a) Identify the type ofreaction, and (b) Write the complete and balanced equation and the chemical names of the reactants and products to support your answer in (a). 5. The equation below shows the precipitation reaction of copper nitrate and potassium iodide. To 2.0 ml of 0.50 McuoNosoh is added 50 ml of 0.5 M Ku solution. Calculate the theoretical mass of copper iodide (Cu) precipitate that is formed. 6. To deliver a 5.00 mL liquid sample most precisely, which piece of glassware would you use? (b) graduated cylinder (a) volumetric flask (c) glass dropper (c) volumetric pipet

Explanation / Answer

First the answer to question 3.

The reaction between copper and sulfur needs energy because of the structure of the product.

The principal product of this reaction is Cu2S. the reaction is this.

Cu0+ S8 ---------> Cu2S(s)

Ths structure of Copper sulfide cristallizes in a hexagonal crystal system. So,l to form this type of bonds, we need an amount of energy.

4. The reaction between Pb(NO3)2 + KCl is a reaction of precipitation.

The precipitate formed it is the PbCl2. Balance of reaction.

Pb(NO3)2 + 2KCl------> 2KNO3 + PbCl2 We know that the product is the plumber chloride because all the compunds with block p (Pb, Bi, Sn, etc) bonded with halogens will produce precipitates.

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