This page describes how to perdevelop a flame test for a variety of steel ions, and also briefly discusses just how the flame shade arises. Flame tests are offered to identify the existence of a fairly tiny variety of steel ions in a compound. Not all steel ions provide flame colors. For Group 1 compounds, flame tests are commonly by far the most basic means of identifying which metal you have actually obtained. For various other steels, tright here are typically other simple techniques that are even more reliable - yet the flame test have the right to give a valuable hint as to wbelow to look.

You are watching: 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 also Annabelle Baker from the Diamond Light Source. Confirm the colors via the facets on Table (PageIndex1).

Practical Details in Carrying out Flame Tests

Clean a platinum or nichrome (a nickel-chromium alloy) wire by dipping it into focused hydrochloric acid and also then holding it in a warm Bunsen flame. Repeat this till the wire produces no shade in the flame. When the wire is clean, moisten it aacquire in the acid and also then dip it into a small amount of the solid to be tested so that some sticks to the wire. Place the wire ago in the flame. If the flame shade is weak, it is frequently beneficial to dip the wire ago in the acid and put it earlier right into the flame as if cleaning it. This have to create an extremely short but intense flash of color.

Tright here will certainly, in reality, always be a trace of oselection in the flame if you usage nichrome. Platinum is a lot much better to use but is much, much more expensive. If you have an especially dirty little of nichrome wire, you have the right to simply chop the end off. You execute not perform that with platinum! Dilute hydrochloric acid deserve to be supplied instead of focused acid for safety and security reasons, yet does not constantly give such intense flame colors.

The colors in Table (PageIndex1) are just a overview. Almost everybody sees and defines colors differently. I have, for example, used the word "red" numerous times to define colors that deserve to be quite different from each other. Other human being usage words prefer "carmine" or "crimson" or "scarlet", however not everyone knows the distinctions between these words - specifically if their initially language is not English.

See more: Advantages And Disadvantages Of Homogeneous And Heterogeneous Groups

Table (PageIndex1): Flame colors of common elements 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 (regularly through white flashes)
Lead gray-white

What execute you execute if you have a red flame shade for an unwell-known compound and also perform not know which of the miscellaneous 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 the unknown compound side by side until you have an excellent enhance.