The Chemistry of Christmas

The Chemistry of Christmas

Noses are red, candles ignite, your puds on fire, its Christmas right?!

Candles
I can’t help but notice the growing trend of candles. People just seem obsessed with them. This Christmas I am sure you will have a Christmas themed candle on your dinner table. Fancy impressing your family with a fascinating and awesome trick?

Candles are made from a mixture of long-chain alkanes, which combine to form the paraffin wax. Alkanes are hydrocarbons which are saturated. As you light the candle, you will trigger an exothermic chemical reaction. Remember an exothermic reaction is one that produces heat and takes in energy! This is why we feel warmth from a candle! The chemical reaction is between the wax and the oxygen in the air. As this is a complete combustion reaction, it would of course produce water (in the form of steam) and carbon dioxide. But what is the smoke from a candle (you may ask)? The smoke is made in the yellow part of the flame where not enough oxygen is available for perfect combustion to take place. The smoke consists of tiny particles of solid, unburned carbon from the wax. The steam produced in the reaction is made from the blue part of the candle flame. This is because the blue area is where the wax burns cleanly with plenty of oxygen.

And now for the trick to excite your unknowing friends and family… First blow out your candle. You should notice the smoke rising from the extinguished wick. But amongst the smoke you won’t be able to see the paraffin vapour, which also rises from the hot wax. This vapour is flammable, meaning you could hold a lit match over the smoke (about an inch away from the wick) and poof! The flame will make an impressive return as it catches the paraffin vapour and the candle reignites! 

 

Christmas pudding

Once your food baby is at least six months old after indulging in the honey roasted turkey, roast potatoes and parsnips, you are all set to proceed in the pregnancy. The dessert! No amount of fullness can tempt you out of eating a bit of Christmas Pud! It is traditional for brandy to be poured all over the pudding and then ignited with a flame. This leaves a blue glow to mesmerise all your family feasters. One of the things that has always puzzled me though is: why does the pudding not burn?

The reason: The brandy is 60% water so the energy from burning the alcohol is absorbed by this water. The water then evaporates, which prevents the pudding from burning to a crisp (hence why the temperature of the pudding is kept low). This is similar to our own body when it sweats. The sweat evaporates allowing you to stay cool. (Ok ok, enough with the analogy between food and sweat). Finally, the alcohol burns off before the water has evaporated, meaning you get left with a somewhat damp, soggy pudding. Still appetized?

Another question you may have is: Why is the flame blue? The brandy burns this colour due to the sugar infused in it. As you may have learnt in your science lessons, different chemicals burn to produce different colours. For example, potassium chloride burns purple and copper sulphate burns green! But don’t go adding these chemicals to your food, they are toxic to the human body…

 

 

Brussel Sprouts

No Christmas dinner is compete without the good old Brussel sprouts. As a vegetable, it is no shock that they are jam packed with nutrients like Vitamins A and C, fibre and folic acid. Have your family chefs ever overcooked these healthy emeralds, leaving a pungent smell? This smell is created due to the organic compound ‘glucosinolate sinigrin’ which contains sulphur. It is the sulphur in the Brussels that leave the unpleasant smell. But next time your Mum tells you to eat your Brussels on Christmas day remember that it is the smelly sulphur chemical that is also responsible for its cancer-fighting characteristics.                                                                                                                                                   Brussels are a bit like marmite. But whether you love it or hate them, it is down to your genes. Yes you heard me right. This almighty veggie has a chemical in it which tastes bitter to a person with one version of a gene, and people with a different gene can’t even taste it at all. Weird huh? So which gene do you have?

 

Rudolf’s Nose

Most of us can’t remember all those reindeer names, but anyone who forgets Rudolf must be one mighty scrooge. If I asked you to describe Rudolf to me, I bet you would say: “He has a bright red nose!” But why is his nose so bright? Does he have the flu? Well Reindeers have a lot of membranes in their nose which act as heat exchangers. This means that the air is rapidly warmed as it enters Rudolf’s nose, and cooled when it leaves. This allows Rudolf and his pals to retain heat and reduce moisture. Handy for when you are stuck in the North Pole 364 days a year… But beware, because this moist and warm environment is home to bacteria and nasty parasites. This could give the reindeers an infection, providing us the reason as to why Rudolf has a bright red nose. Aww poor Rudolf.