Observing The Flame Colour

The Chemistry of Art > 2. The Structure of the Atom and Colours > Observing The Flame Colour >

Perform first-hand investigations to observe the flame colour of Na⁺, K⁺, Ca²⁺, Ba²⁺, Sr²⁺, and Cu²⁺

Objective: To observe colours produced by excitation of metal ions through heating

Methodology:

1. Use a pipette to place a drop of metal nitrate solution in clean wire loop
2. Suspend the drop of solution at the edge of blue flame of Bunsen burner
3. Record the observed flame colour
4. Use a spectroscope or diffraction grating to observe for the colour of flames
5. Record the flame colour observations

Reliability:

• Repeat experiment at least 5 times or until three sets of consistent results are achieved

Accuracy:

• The use of spectroscope and diffraction grating allow more precise quantitative data to be gathered

Validity:

• Control: Use same concentration of solution, identical anion, same heat source and fuel, same Bunsen flame colour