16.8.11: Lab activity at PSN

We went for our third lab activity in Pusat Sains Negara. 
1) Rainbow
2) Rubber ball

The facilitator started with some interactive games. Finally, I manage to find out how he did this!
1) Making a rainbow
These are water dyed with food coloring and mixed with different density of ethyl alcohol, in bottles labelled from A to E.

Coloured liquid with different density. They were labelled from A to E. 

We had to slowly squeeze coloured liquid into a test tube. There is a technique to do it. 
We need to slant the test tube and slowly drip the liquid into the test tube, drop by drop using a pipette. The less dense solution is placed on top of the more dense solution, resulting in a 'rainbow' effect.
We didn't follow the instructions and missed a colour. 

2) Making a Rubber ball
This is about the concept of polymers. Polymers are long chains of repeating molecules, which can stretch and bend. 

  • White glue (2 table spoon)
  • Borax
  • Water
  • Food colouring
  • Plastic stirrer
Pour a 2 tablespoons of white glue into a small container.
Add in 5 ml of water and stir using a plastic stirrer. 
Mix it with a few drops of food colouring.
Add in 5 ml of borax and stir it. It turns into semi solid. 
Then add in 5 ml of borax and stir it again. It turns into solid. 
Finally, add in 5 ml of borax and stir it again. It turns into a solid rubber ball.

Take it out and it roll it to make it into a ball. 

We used different colours to make the rubber ball. 

The ball can even bounce. 

We had to redo this several times, before we could get the correct consistency. 

Caution: The ball will melt, so keep it in a container. It will assume the shape of the container.
We kept it in the refrigerator. We later found that it could be molded / rolled into shapes like ball, sausage, and flat like a lollipop.  

After that activity, we went to the science centre exhibit area. The boys observed the exhibits on frogs. 
The bullfrog is bigger than E's hand. 

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