The chemical reactions:
CuSO4(aq) + Zn(s) → ZnSO4(aq) + Cu(s) Zn(s) + H2SO4(aq) → ZnSO4(aq)+ H2(g) The copper on the surface quickly reacts with oxygenaccording to the following reaction: 2Cu(s) + O2(g) → 2CuO(s)
Experimental Procedure Dissolve
completely about 0.5 to 0.7 g of copper (II) sulphate pentahydratein about 10 to 20 mL of deionized water. Calculate the amount ofzinc powder that must be added to a copper sulfate solution so thatthe sulfate completely reacts. This calculated mass of zinc, plusan extra 0.01 g, is added to the copper sulfate. Stir. When thereaction appears to be complete (what signifies this?), add enoughsulfuric acid to create a colourless solution. What is the purposeof this step? Suction filter the final product. Wash with about 5mL of ethanol. Maintain suction for about 10 minutes. Determine themass of the final product to 2 significant figures. Reagents 0. 6 gCopper (II) sulfate pentahydrate (CuSO4(s)) (FW = 249.68) Zincpowder (FW = 65.41) Sulfuric acid (1.5 M H2SO4(aq)) Ethanol
Data Mass of CuSO4 = 0.61g Mass of Zn = 0.17g Mass of emptywatch glass = 48.72g Mass of watch glass and Cu = 48.91g
Questions:
1. Please show the calculation for the amount of Zn added to thereaction mixture and for the percentage of Cu recovered from theoriginal copper sulfate sample (theoretical yield).
2. What is the purpose of adding enough sulfuric acid to createa colorless solution?
