The atoms in AAS

[monokekie]

hey guys,

In AAS, the metal ions are reduced as their oxidation number reduces to zero due to the atomisation process. But what acts as the reducing agent and what acts as the oxidising agent in this process?

[Mao]

The oxidant (oxidising agent) is itself reduced. In this case, this is the metallic ions.

The reductant is the fire (or chemical reactions in the fire). E.g. say the flame is from burning natural gas, CH4.




Normally the above pair occur in 1:1 ratio. With the addition of metallic ions, this is disrupted, some electrons produced from the first equation goes on to reduce the metal. Hence the flame (the combustion process) gives an environment that has electrons zooming around everywhere, which can get picked up by the metallic ion.

[monokekie]

pro.......*speechless*

thanks mao!

[Dark Horse]

On the topic of AAS, what is the sample state in AAS?

[Gloamglozer]

On the topic of AAS, what is the sample state in AAS?

It has to be gaseous and an element to be analysed.  Is that what you meant?

[NE2000]

By my understanding you take the chloride of a metal ion (done by dipping into HCl) and then place it into the burner where some complex process involving the word plasma will basically separate the metal cation and the chloride anion and subsequently reduce the cation into its ground state metal atom (atomisation). This ground state metal atom can then be excited by the wavelengths of light that are being directed towards it from the hollow cathode lamp made out of that same metal. Is that right?

Another question though related to AAS. I read some notes that said the monochromator after the burner was used to select a wavelength that is only absorbed by the metal you want, but I thought the design itself (with the lamp being made out of the metal you want) catered for this, as no other metal in the sample would absorb the same wavelengths emitted by the metal that is being excited by high voltages in the lamp? So why exactly is the monochromator placed there?

[Mao]

A type of metal would emit and absorb a few distinct wavelengths. For accurate and reliable analysis, a monochromator is used to select one of these wavelengths.

[chem-nerd]

also, the flame itself emits visible light