Flame Test

Flame Colours

From video:

Alcohol - blue

Barium - yellow

Boron - green

Calcium - orange

Sodium - yellow

Copper - green

Potassium - lilac

Zinc - yellow

Found these on another website! Very detailed:) :

RedCarmine to Magenta: Lithium compounds. Masked by barium or sodium.Scarlet or Crimson: Strontium compounds. Masked by barium.Red: Rubidium (unfiltered flame)Yellow-Red: Calcium compounds. Masked by barium.Yellow

Gold: IronIntense Yellow: Sodium compounds, even in trace amounts. A yellow flame is not indicative of sodium unless it persists and is not intensified by addition of 1% NaCl to the dry compound.WhiteBright White: MagnesiumWhite-Green: ZincGreenEmerald: Copper compounds, other than halides. Thallium.Bright Green: BoronBlue-Green: Phosphates, when moistened with H2SO4 or B2O3.Faint Green: Antimony and NH4 compounds.Yellow-Green: Barium, manganese(II), molybdenum.BlueAzure: Lead, selenium, bismuth, cesium, copper(I), CuCl2 and other copper compounds moistened with hydrochloric acid, indium, lead.Light Blue: Arsenic and come of its compounds.Greenish Blue: CuBr2, antimonyPurple
Violet: Potassium compounds other than borates, phosphates, and silicates. Masked by sodium or lithium.Lilac to Purple-Red: Potassium, rubidium, and/or cesium in the presence of sodium when viewed through a blue glass.

Questions:

1) How and what is it used for in "crime scene investigations/forensic science"?

Flame analysis is based on the physical and chemical principle that atoms—after being heated by flame—return to their normal energy state by giving off the excess energy in the form of light. The frequencies of the light given off are characteristic for each element. Hence, it is used to identify different elements of substances. Since different elements produce different colours when heated with a flame, the colours produced can be compared to known standards and the presence of certain elements in the sample can be confirmed. Flame tests can also be used to determine the presence of metal elements in water by measuring the spectrum produced by the metals exposed to flame. The water is vaporized and then the emissions of the vaporized metals can be analyzed.

However, as useful as it is to forensic analysis, the flame test does not work on all elements. It cannot detect low concentrations of most ions and impurities can greatly affect the test results. For example, sodium is present in most compounds and can colour the flame.

2) If there are more than one trace metal present, is the flame test still a suitable technique to identify the trace metals?

It depends on the substances being used. As mentioned above, as many compounds are often contaminated with sodium, a cobalt blue glass can be used to

filter out the yellow flame and expand the ability to see violet and blue hues. For other trace metals however, the flame test is not a suitable technique to identify them as the flame would be seen as a mixture of many different colours.

Usage of cobalt glass:

3) Is flame test sufficient to identify the trace metal(s) present?

Not entirely. Many trace metals produce the same types of colours and some do not change the flame colour at all.

4) What is a "Mass Spectrometer"?

It is a machine that is used to determine chemical analytes in a chemical sample. Some are small enough to fit on a table, while others are so large that they fill entire rooms.

• A sample is loaded onto the MS instrument, and undergoes vaporisation

• The components of the sample are ionized by one of a variety of methods (e.g., by impacting them with an electron), which results in the formation of charged particles

• The ions are separated according to their mass-to-charge ratio in an analyzer by electromagnetic fields

• The ions are detected, usually by a quantitative method

• The ion signal is processed into mass spectra

(http://en.wikipedia.org/wiki/Mass_spectrometry)