Community Carbon Offsetting Hong Kong

As part of Earth week, one of the year 9 classes at Sha Tin College played the Cap and Trade game. All went well with the game, but we did have some fun with the visual demonstration of cap and trade at the end.

We took a water bottle filled with a mixture of sodium bicarbonate, red food colouring and a drop of detergent and then added some vinegar.  The vinegar reacts with the sodium bicarbonate to produce bubbles of carbon dioxide, and a few doses of vinegar generates enough foam to push the cap off the top of the bottle providing a visual demonstration of exceeding the cap in Cap and Trade.  In this case however, the premixed bicarbonate and food colouring proved initially unreactive, prompting the addition of more vinegar.  Finally it seems that the reaction remembered that it was supposed to happen and all of a sudden there was a lot of foam.

Thanks to Morag Brookes of Sha Tin College for all the arrangements and to Sam Bevan for the idea of the demonstration.