Aluminum pieces inadvertently collect on the filter. a. If left on the filter, w

Question

Aluminum pieces inadvertently collect on the filter. a. If left on the filter, will the percent yield of the alum be reported as too high or as too low? Explain. b. If the aluminum pieces are detected on the filter, what steps would be used to remedy the observation? Explain. 3. In a hurry to complete the synthesis, Jerry used 6 M HCl, also on the reagent shelf, instead of the 6 M H_2SO_4. As a result, describe what observation he would expect in Part A.6. Part A 4. Andrea used too much sulfuric acid. What observation would she expect in Part A.6? Explain. Explain why the alum crystals are washed free of impurities with ethanol-ice-water mixture rather than with room-temperature deionized water. Part A 8. Explain why a percent yield of greater than 100% might be reported for the synthesis of an alum. Part B.2. Explain why the melting point of your prepared alum must either be equal to or be less than the actual melting point of the alum. Consult with your laboratory instructor.

Explanation / Answer

2.a.If Aluminium pieces are left on the filter,the percent yield of the alum will be reported as too low.The aluminium pieces which have not been converted to alum will automatically bring down the value of actual yield.Since percent yield=(actual yield/theoretical yield)*100,lowering of actual yield will decrease the percent yield.

b.The aluminium pieces should be collected and then treated with hot concentrated KOH followed by treatment with conc H2SO4 to convert the aluminium pieces to alum.Once the alum crystals are formed,vacuum filter them over the same filter paper (one containing the bulk alum) and then find out the actual yield.

7.The presence of impurities lower down the melting point of a solid compared to that of the pure solid.So if the m.p of your alum is equal to the actual m.p then the alum is 100% pure i.e there are no impurities.If the observed m.p of prepared alum is less than the actual m.p ,it suggests the presence of impurities.(the higher the amount of impurities,the lower the m.p compared to actual m.p of alum).

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