Elemental Analyses - Video Clip Showing Flame Colours

In the previous post promised I would explain how one can use flame colours for analysing elements.

Just as we all have finger prints, DNA, irises etc. that can be used to identify us, or to catch criminals, so each element has its own characteristics that we can use to track it down.
You saw the flame colours in the previous post - those are specific characteristics we can use to find out if an element is in a sample, be it beer, metal, or a carrot.

To analyze we would have to get some of the sample into a flame to free up the elements and allow them to emit their specific colour of light. In simple mixtures and pure compounds this method gives us a way to ID a few elements. In more complex cases we need the help of instruments.

When heated sufficiently most elements actually produce a range of colours and some colourless ultraviolet light. We can use devices such as prisms to separate the light and then use a very sensitive device to measure how much of each specific colour (or wavelength) of light there is in the flame(an the original sample).

There are many different types of instruments that use flames, microwaves, or even arcs, sparks or plasmas to make a cloud of atoms. In the iron and steel industry, for instance, there are arc instruments that make a continuous arc (similar to electrical welders). The arc vaporises some of the metal being analysed and it emits light according to its elemental makeup. In a short space of time the instrument separates the light using prisms or gratings and measures how much light there is of each colour or wavelength - from this information we can get a report of the amount of each metal or other elements that are in the sample being analysed. Its really quick - back in the old days it took perhaps a few days to get the same result using other chemical methods.

In our Analytical Chemistry Course students make use of many simple and complex instruments for analysing elements. Some of these instrument may cost as much as 1.5 million rands or even more depending on complexity and technology.
I asked my 3rd year analytical students to give a brief demo of how these flame colours can be used in analyses on a flame instrument. Its their first filmshow, Take #1
Let's see what they have to say...

Thanks for that Ludwe and Luzuko - not bad for the first attempt.

That instrument was a flame spectrometer with an air acetylene flame at about 2400 DegC into which they fed copper and strontium dissolved in water.

Next post I want to talk about Your elemental make-up.

Till next time,

Gletwyn