Describe all possible physical, chemical and biological changes that can occur f

Question

Describe all possible physical, chemical and biological changes that can occur for the following compounds during the sample holding period: (a) Oil, (b)S2, (c)CN-, (d) phenols. Describe all possible physical, chemical and biological changes that can occur for the following compounds during (he sample holding period: (a) chlorinated solvents, (b) PAHs. (c) metals. Explain why: (a) HNO3 rather than other acids is used for metal preservation; (b) amber bottle is preferred for PAHs; (c) zero-head space container for groundwater samples collected for tetrachloroethylene analysis.

Explanation / Answer

Oils:

Over a period of months this will dramatically speed up the process of oxidation (deterioration) due to them continually heating up and cooling down.

S2-

It is vital that liquid sulphur be stored and transported at carefully maintained temperatures, above 130º C. If we do not maintain less temperature build-up of vapours that can accumulate above the sulphur in tanks.

CN-

Hydrogen cyanide gas may form.

Phenols

Phenol is caustic and causes corrosion to the storage vessel.It emits fumes on storage which are poisonous.

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