Vinegar cork gun

We took some bicarbonate of soda and put it into a plastic bottle.  Dad said we must use a plastic bottle because a glass bottle is very dangerous if it breaks.

When there was enough bicarbonate of soda in the bottle we added some vinegar, and quickly put a cork into the bottle.

Very soon it went pop, and the the cork shot out of the bottle.

We tried again, but did not have enough vinegar, so we mixed some lemon juice with the vinegar.  This time the mixture in the bottle made lots of bubbles, but the cork stayed in so I picked up the bottle and gave it a good shake.

Very soon the cork popped out and went flying across the garden.

Bubbles and surface tension

The other weekend, we decided to learn about surface tension.  I took a plastic plate and filled it with water, then sprinkled pepper on the surface of the water.

Once everything was still, I added a few drops of dish washing liquid and watched the pepper speeding around the surface of the water as the soap changed the surface tension.

I wanted to make patterns, so I added some food colouring to the water.  The green colour just sank to the bottom.  It was boring, so to make it fun again, I took a straw and started blowing bubbles.  That was the best part.