Read an authoritative source for a discussion of the techniques to be used in th

Question

Read an authoritative source for a discussion of the techniques to be used in this experiment. Safety is a very important aspect of experimental design. Explain why it would be dangerous to pour 100 mL of a 0.10M Cr(NO_3)_3 solution into the drain. Suggest a way that Cr^3+ ion could be removed from the solution as a solid, so that the solution could be disposed of and the solid sent to a chemical landfill. A solid is known to be either BaCO_3 or CaCO_3. It is dissolved in 6M acetic acid. A pale yellow precipitate forms when K_2 CrO_4 solution is added. The subsequent flame test with that precipitate shows an orange-red color. Which cation is present? Briefly explain.

Explanation / Answer

1. Cr(NO3)2 have serious medical effects as it acts as a mutagen, substances that have the ability to change the genetic code of the body. It is thus advised not to drain the Cr(NO3)2 chemical into the drawin. Also, the Cr3+ may react vigorously with any flammant to cause fire and this is another reason and precaution must be taken to not dispose the material by draining.

2. Cr3+ in Cr(NO3)2 (aq) can be isolated from the solution by precipitating the cation in the form of a hydroxide Cr(OH)3 by reacting the nitrate salt with NaOH. The solid thus formed Cr(OH)3 is insoluble and can be filterted out from the solution easily.

3. Ba(CrO4)2 burns in flame with a organce-red coloration. Thus the cation present here is Ba2+.

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