Using Color Changing Candles to Decrease the Hazards and Increase the Accessibility of the Rainbow Flame Test

Abstract

Colored flames like those in the rainbow flame test are fascinating for all ages and can spark meaningful conversations about chemistry concepts. However, the rainbow flame test can be very dangerous, a fact too often ignored by those wanting to see the flame change colors. Previous work found that the safety of this demonstration could be increased by introducing aqueous solutions of salts into the flame via small spray bottles. The largest safety hazard that remains is the use of gas to produce the flame in a Bunsen or Meker burner. A potential solution to this issue is a color-changing candle, one that still exhibits a color related to a metal ion that can be used for demonstration purposes. Through using a small candle that already contains a salt the need for a gas source is eliminated, as well as the need to introduce the ions into the flame. These candles could easily be prepared by teachers and hold the potential to provide a safer means of conducting this demonstration over a long period of time, which would increase the accessibility of this demonstration to educators with limited time and resources.