Do try this at home. A guest post by Penny Carmichael

The festive season is upon us, and what better way to celebrate than with some incredible feats of science? We’ll take you from presents, to decorating, to dinner and finally to evening entertainment with these amazing science experiments.

1. Cut Glass

You will need; a glass bottle, string, scissors, nail varnish remover, a lighter, cold water.

Short on present ideas and cash this Christmas?  Make your friends some stylish pen pots out of a few old beer bottles. Take some string and cut a piece large enough to fit around a beer bottle. Soak the string in some nail varnish remover (this is basically acetone) and tie it around the bottle, snipping off the excess string. Now for the fun bit! Set fire to the string (careful not to burn your hands) and once the flame goes out dunk the bottle into cold water. The glass expands when it is heated by the flame, then rapidly contracts in the water and should make a clean break under the string!

Rating 3/5 – an impressive trick to show friends but the edges of the glass can be sharp so smooth them with a little wet sandpaper. The thinner the glass the better, thick bottles can need an extra tap.

The heat from the flame causes the glass to expand..

2. Balloon Skewer

You will need; a balloon, a wooden skewer, Vaseline.

Make hanging decorations even more fun with this mind-boggling trick. Blow a balloon up to about half full and tie. Coat the tip of a wooden skewer in a little Vaseline and carefully insert it into the balloon near the knot. Twisting, push the skewer through the balloon and out through the darkest part of the top and you will find the balloon will not pop. Balloons are made of long polymer chains which are stretched when the balloon is blown up. The polymer is least stretched near the knot and at the top of the balloon, and so the skewer can be inserted here, pushing the chains apart without bursting the balloon.

Rating 4/5 – easy and effective, a sure crowd pleaser.

3. Chemistry Fire Extinguisher

You will need; candles, a jug, bicarbonate of soda, vinegar.

Why not make your Christmas dinner a little atmospheric with a candle or two, as well as giving yourself yet another opportunity to show off your science skills?  Put a little bicarbonate of soda (baking powder) in a jug and add a generous glug of vinegar. These will react together giving off carbon dioxide which is heavier than air and so stays in the bottom of the jug. Pour the gas from the jug onto the candles and they will be extinguished as the flame is starved of oxygen.

Rating 3/5 – cool, but lost a couple of points as I managed to soak one of my candles in vinegar – not so impressive.

4. Instantly Freeze a Beer

You will need; a beer (preferably in a clear glass bottle), a freezer.

A great party trick. Place a beer in the freezer for a few hours (three seemed to do the trick for me) until it is cold but not yet frozen. Remove the beer and open it being careful not to disturb the liquid. Give the beer a sharp knock, (on the rim of the beer using another bottle works well) and watch as the beer freezes in an instant! The beer becomes supercooled whilst it is in the freezer, that is, its temperature is below zero but it is still a liquid. When you tap the bottle you release bubbles which provide a nucleation site for the ice crystals to form and the beer quickly freezes.

Rating – 4/5 at least no one can complain about you serving them warm beer! And don’t worry, once the beer thaws it is perfectly drinkable and not too flat.

5. Soda-Mentos Geyser

You will need; a two litre bottle of diet fizzy drink, a packet of Mentos.

And finally, make your New Year’s Eve go with a bang, without having to splash out on expensive fireworks. Simply dropping a few Mentos into a bottle of fizzy drink causes a spectacular eruption which can reach up to ten metres in height.

Our geyser didn’t quite match up to the Mexican world record…

A trick so popular, that the current world record for the most simultaneous eruptions is a whopping 2,433, set in Mexico City. Physicists at Appalachian State University in Boone, North Carolina studied the reaction and concluded that the jets were caused by the rapid release of carbon dioxide, bubbles of which are formed on the dimply surfaces of the Mentos sweets as they sink to the bottom of the bottle. The coatings on the sweets and the use of diet soda also accelerate the reaction as both factors contribute to a lowering of the surface tension of the liquid.

Rating 5/5 – the most impressive by far. An out and out winner.

 

So there you have it, all you need for a little scientific fun this Christmas. Enjoy!

This is a guest post by Penny Carmichael. Penny is a final year Chemistry student at the University of Bristol. An avid scientist, she is currently carrying out research in
conducting polymers.

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