1. Why do we use oxidizing and reducing flame in different analytical tests?

For example, in the charcoal block reduction test, we use reducing flame. Why? How does this affect the salt to be reduced into metal?

  • $\begingroup$ From Wikipedia: "the oxidizing flame is usually undesirable for welding and soldering, since, as its name suggests, it oxidizes the metal's surface." " The reducing flame is also called the carburizing flame, since it tends to introduce carbon into the molten metal." Here is the link: en.m.wikipedia.org/wiki/Oxidizing_and_reducing_flames $\endgroup$ – Aditya Dev Mar 1 '16 at 13:16
  • $\begingroup$ I need detailed explanation as to why we are using it $\endgroup$ – Rafat Mar 1 '16 at 13:20

As the name suggests the oxidizing flame is used to oxidize probes, while the reducing flame is used to reduce probes. Hereby oxidation is done by oxygen, while reduction is done by reducing agents in the flame, such as carbon monoxide or hydrogen.

In the charcoal block reduction test with a blowpipe one often will oxidize the probe in the first step to get rid of nonmetal elements in the probe, and then will use the reduction flame to reduce oxidic metal compounds in the melt to the elemental metal. Volatile metals will hereby be precipitated at the colder regions of the charcoal as oxides. Metal and oxide precipitate can then be further analyzed.


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