From the enticing aroma of the turkey in the oven to the “whoosh’” of the flames as the brandy-soaked pudding comes alight, Christmas is a wonderful time for the senses. But have you ever considered the science behind our best-loved festive traditions? Here is one of my seven food and flammable favourites: The others can be found on this website.
Candle-lit carol services are part of Christmas for many people, as are the ones entwined in holly on the table. Traditionally beeswax was used but while it gives great flames, it is rather expensive. Nowadays the vast majority of candles are made of paraffin wax obtained as one of the products of oil refining. These waxes are hydrocarbons, molecules made of two different elements: carbon and hydrogen.
When you light a candle, wax is melted, and the molten wax gets drawn up the wick, which gives a larger area for the wax to evaporate. It is the gaseous wax that burns, forming carbon dioxide and water, and giving out energy, which is where the heat and light come from.
But not all the carbon atoms get turned into carbon dioxide at one go – it is carbon-rich soot particles glowing hot that give out the yellow light that characterises a candle flame.