Wow. Things have been fizzing in the Middle Syndicate lately with us all creating chemical reactions we won’t soon forget. The main ingredients? Diet Coke and Mentos mints of course!

PSSSSSSSSSSSSSTT. What’s that sound? It’s called Carbon Dioxide, CO2 and that’s the gas that makes all those bubbles in fizzy drinks. We heard some CO2 escaping as we carefully undid the lids on our Diet Coke bottles. Then, we carefully screwed on an apparatus called a Geyser Tube that attaches to the coke bottle, holds the mentos and acts like a fountain when the coke comes rushing out.

Next, we had to gently load 9 or 10 mentos into the geyser tube remembering to make sure the pin was in to stop the mints falling in early. Finally, screw on the top cap, a short countdown and PULL THE PIN! THE MINTS FALL IN! COKE EXPLOSION!

How did that happen?

When the Mentos hit the Coke things start happening quickly. First, the sugar in the Mentos makes the water molecules in the Coke ‘relax’ and they stop ‘holding hands’.

This allows the CO2 to move around more freely. The CO2 is attracted to the surface of the Mentos because the sweets are covered in tiny divots (craters). The CO2 continues to rush onto the Mentos creating a massive ‘dogpile’ of bubbles. The bubbles expand in the blink of an eye and have nowhere to go except up! Woosh! Out flies the CO2, the H20 and all that flavouring in a Coke fountain.

Interesting

The (secret) chemical mix of Diet Coke seems to work best. We tried a regular sugar soft drink with sugar but that was a fizzer. Coke and Sprite No Sugar worked well so it might have something to do with artificial sweeteners? We tried mint and fruit flavoured Mentos too and they all worked as well as the original flavour.

Tea Bag Rockets

If you’ve got a cold room, here’s a cool trick you can do with a tea bag. It can’t be just any tea bag, it needs to be a double one that’s held together by a little staple. Cam says Red Seal - Red Bush tea bags are pretty good.

To begin with you gently pull the tea bag apart; so you are left with a paper tube. Empty the tea out and put your finger in the tea bag to make it a tube. Place the tube on its end on a saucer or plate. You must be really careful to not let any breeze or moving air knock the tea bag over. Then you light the tea bag so it burns evenly down. Once burnt the tea bag leaves a little bit of ash which flies up into the air like a (slow) rocket. Then the ash gently falls back to the ground. Pretty cool.

What’s Going On?

The air molecules inside the tea bag heat up and begin moving around quickly. The molecules also spread out and become less dense (‘lighter’) than the cooler air molecules around them. The warmer air molecules rise and create a warm air current that lifts the now very light, tea bag ash upwards. When the air molecules cool down the tea bag ash floats back down to the ground. Cup of science anyone?