Rainbow flame is a colorful reaction.  This reaction shows you how different salts of different ions gives you different colored flames.

In this experiment we pour methanol to different salts with no net electric charge and ignite them. This reaction is a violent reaction. methanol is a highly flammable material.

Safety First! Adult supervision required. Wear protective eye wear and clothing. Don’t eat/drink your experiments.

Materials and tools required

Chemicals:

  • Potassium chloride
  • Sodium chloride
  • Strontium
  • Copper suplhate
  • Lead nitrate
  • Boric acid
  • Methanol

Apparatus

  • Glass Petridish – 6
  • Beaker
  • Plastic spoon
  • Pipette

Video on the YouTube for experiment

What to do!

Step 1 – Take around 20 gm of sodium chloride in a petridish.

Step 2 – Similarly put potassium chloride, strontium, copper sulphate, lead nitrate and boric acid in 5 different petridishes.

Step 3 – Pour few drops of methanol in each petridish.

Step 4 – Light the methanol to start the fire.

Step 5 – Put off the lights to get a better look of these colorful flames.

Images for instructions

Working principle of the activity

We get colorful fire by igniting metal salts soaked in methanol. These metal salts are made from pairs of ions — atoms with electrical charges. This pairing creates a salt with no net electrical charge.

The color in the burning salts comes from the energy contained in their electrons.These electrons become excited when energy is added — for instance, when you set the salt on fire. As the salt burns, the extra energy is lost — as light.

Color of that flame depends on the amount of energy being released. Sodium Chloride burns yellow. The flames coming off of copper are bluish-green. Potassium burns violet.

With all of these salts burning different colors, we get rainbow flames.

Safety Precautions

  • Methanol is highly flammable. Do not pour it directly from the bottle, use a small measuring beaker to pour.
  • In addition to performing the project on a heat-safe surface, it’s a good idea to do it in a well-ventilated area, under a fume hood, or outdoors. There may be a small amount of smoke.
  • Do not add fuel to the fire while it is still burning. Wait until the flames are extinguished and then add more alcohol and re-light the fire.
  • The flames are easily extinguished by suffocating them (as with the lid of a pan).
  • It’s a good idea to wear protective eye wear and clothing, as for any science demonstration. Avoid wearing synthetic fabrics, as they readily melt if exposed to flame. Cotton, silk, and wool are good choices, or you can wear a lab coat.