Answer to Question #163889 in General Chemistry for Laial Mohmed

Question

describe how to do a flame test on a sample of salt

Answer 1

Introduction

When a metal salt is sprayed introduced onto flame the electrons in the metal are excited and jump from one electron shell level to the next higher shell level (excited state). They however cannot remain there so they have to return to their original shell (ground state). As they do so, the energy they gained earlier is lost in the form of light (emission). Hence a characteristic color of flame is produced.

Materials

Nichrome/platinum wire

Bunsen burner flame

Method

• dip the clean wire loop into the solid sample of the compound being tested
• put the loop into the edge of the blue flame from a Bunsen burner
• observe and record the flame color produced

Expected results

The table shows the flame test colors for six common metal ions.

Ion present Flame test colour

Lithium, Li⁺ Red

Sodium, Na⁺ Yellow

Potassium, K⁺ Lilac

Calcium, Ca²⁺ Orange-red

Barium, Ba²⁺ Green

Copper, Cu²⁺ Blue-green