Around this time of year, houses in Anaheim Hills start putting out candles for the holidays and this creates Chemistry.  Whether lighting candles on the Menorah for Hanukah, adding candles to a Santa Lucia wreath, or decorating the house for Christmas, homes seem to be full of lights.  Using Chemistry, we can understand why a candle burns.

Chemistry students may wonder why doesn’t the candlewick burn up?

Why can’t we light wax on its own without a wick?  Is it the wax that’s burning, or wax vapor?  A Chemistry Tutor can explain the process and even help set up a Chemistry lab to show how a candle works.

There are two parts to a candle – the fuel, which is usually wax, and the wick, made of some sort of absorbent twine.  A chemical reaction helps the two work together.

The wick needs to be absorbent, just like a towel, in order to soak up the fuel.  Also, it needs to have a strong capillary action in order to “suck up” the fuel.

Your Chemistry Tutor might bring over a length of un-waxed wick…

available at most craft stores, in order to create a wick for the candle in your Chemistry lab.

There are many types of wax that can be the fuel.  Beeswax or Paraffin is often available at craft store in Anaheim Hills or places like the Lowe’s in Fullerton or the Home Depot in Anaheim Hills.

To create the candle, the Chemistry Tutor will

help your student add wax to the wick, then insert it into the beeswax or paraffin.  He or she may also bring over a regular candle in order to compare the two.

When the Chemistry student first lights the wick, the wax close to the wick melts.  Through the chemical process of capillary action, the wick begins to absorb the liquid wax and pulls it upwards.  The Chemistry Tutor may point out it’s not the wax that’s burning, but the wax vapor.

Here are two Chemistry experiments that show that it’s actually wax vapor:

  • A Chemistry Tutor may own a metal or glass tube, like a straw.  If this is placed at a 45-degree angle to the candle’s flame, the Chemistry student can then light the upper end of the tube, where the wax vapor is coming out of the tube.  There will be two flames, which is a pretty cool effect.
  • The Chemistry Tutor may then instruct the Chemistry student to blow out the candle, while having a lighter ready.  The white smoke is actually wax vapor.  The Chemistry Tutor can instruct the student to light the smoke, not the wick.  The result of the experiment is that the flame will travel down the steam and relight the wick.

As for why the wax doesn’t burn, this is due to its chemical composition.  It is too dense.  Like cooking oil or motor oil, the wax has to get very, very hot in order to burn.  A lighter isn’t enough to set beeswax or paraffin wax on fire.  This is why a candle works so well.  The wick allows only a tiny amount of wax near the flame.  This amount is small enough that a flame can cause it to vaporize and burn.

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Posted in Anaheim Hills, Chemistry