This web page explains exactly how to percreate a flame test for a variety of steel ions, and briefly discusses just how the flame color arises. Flame tests are offered to determine the existence of a fairly small variety of steel ions in a compound. Not all steel ions offer flame colors. For Group 1 compounds, flame tests are typically by far the most basic means of identifying which metal you have actually obtained. For other metals, tbelow are typically other basic approaches that are even more trusted - however the flame test have the right to give a helpful hint regarding where to look.

You are watching: 3. why does a salt compound give off light (or a colored flame) when burned?

*
Figure (PageIndex1): Colored flames from strontium, cesium, sodium and also lithium (from left to right). Picture courtesy of the Claire Murray and Annabelle Baker from the Diamond Light Source. Confirm the colors via the aspects on Table (PageIndex1).

Practical Details in Carrying out Flame Tests

Clean a platinum or nichrome (a nickel-chromium alloy) wire by dipping it right into focused hydrochloric acid and also then holding it in a hot Bunsen flame. Repeat this till the wire produces no shade in the flame. When the wire is clean, moisten it aget in the acid and then dip it into a small amount of the solid to be tested so that some sticks to the wire. Place the wire earlier in the flame. If the flame shade is weak, it is regularly helpful to dip the wire ago in the acid and put it ago into the flame as if cleaning it. This need to produce a very short yet intense flash of color.

There will certainly, in reality, constantly be a map of oselection in the flame if you usage nichrome. Platinum is much much better to use however is a lot, a lot more expensive. If you have actually a particularly dirty bit of nichrome wire, you deserve to just chop the end off. You carry out not execute that through platinum! Dilute hydrochloric acid have the right to be used rather of concentrated acid for safety and security factors, but does not constantly offer such intense flame colors.


The colors in Table (PageIndex1) are simply a overview. Almany everybody sees and defines colors in a different way. I have actually, for instance, used the word "red" a number of times to describe colors that can be quite various from each various other. Other civilization use words favor "carmine" or "crimson" or "scarlet", however not everyone knows the differences between these words - particularly if their initially language is not English.

See more: Chapter 13 The Federal Bureaucracy Is Best Characterized In Terms Of

Table (PageIndex1): Flame colors of prevalent facets Elementflame color
Lithium red
Sodium solid, persistent orange
Potassium lilac (pink)
Rubidium red (red-violet)
Cesium blue/violet (check out below)
Calcium orange-red
Strontium red
Barium pale green
Copper blue-green (frequently via white flashes)
Lead gray-white

What carry out you do if you have a red flame color for an unrecognized compound and do not understand which of the assorted reds it is? Get samples of known lithium, strontium (etc) compounds and also repeat the flame test, comparing the colors developed by one of the recognized compounds and also the unknown compound side by side till you have an excellent enhance.