Christmas Combustion Chemistry


Want to bring some chemistry to the Christmas
table? In this video, we’ll take a look at three fiery tricks you can try, and the
chemistry behind them. Our first entry is one you might well already
be familiar with: the flaming Christmas pudding. Christmas pudding is a traditional part of
the Christmas meal here in the UK, and it’s also customary to pour hot brandy over the
pudding and set it alight before serving, which is what we see happening here. Of course,
the reason the brandy burns is down to the presence of a familiar chemical compound:
alcohol, or ethanol. The ethanol vapour in the hot brandy reacts with the oxygen in the
air when it’s lit, producing the flickering blue flame. The blue colour of the flame is due to fragments
of molecules absorbing energy from the combustion reaction, putting them into a higher energy
state. When they settle back to their original state, they lose the extra energy as blue
light. If there’s soot present in the flame, the heating of the soot to a high temperature
causes the characteristic yellow flame. However, with complete combustion, as we have with
the ethanol in the brandy, little soot is produced. Burning candles does produce soot, which links
us nicely to our next trick: relighting a candle at distance. You can try this one with
any candle – if you blow the candle out, then hold a lit match in the ‘smoke’ that’s
given off, the flame will ‘jump’ back down to the candle, relighting it. Candles are usually made of paraffin wax,
and this trick works because the ‘smoke’ is actually a mix of wax vapour and a large
number of tiny wax droplets suspended in the air. When you put a match into the smoke,
you’re reigniting this wax, allowing the flame to jump down to the candle’s wick. A third and final Christmas combustion trick
also involves candles – and allows us to turn the humble orange into a festive flamethrower.
To try this out, you simply need a small piece of orange peel and a candle. By taking the
orange peel and squeezing it, we can squirt out the oils within the peel; if we squirt
these oils directly into the candle, we can create an impressive jet of flame! This trick works due to a particular chemical
in the oil of the orange peel: limonene. Limonene’s an important contributor to the aroma of an
orange, and it’s also pretty flammable. When we squirt the oils into the candle flame,
they ignite due to the limonene content, producing the burst of flame. That about sums up our Christmas combustion
chemistry, but there’s plenty more Christmas chemistry over at the Compound Interest advent
calendar. Check it out at the link below, and have a great Christmas!

6 thoughts on “Christmas Combustion Chemistry”

  1. The video is well paced and I like how the usual graphical style of the Compound Interest blog is used in the graphical explanations of the chemicals and reactions. I enjoyed it.

    I don't think I will be trying that orange peel trick any time soon. I do not want to antagonize fire in any way.

  2. great work on the video bud cool topic.
    here's one you can explain… orgon energy (excuse the spelling) both positive and negative and if possible the effects on the human body

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