16.8.11: Lab activity at PSN

We went for our third lab activity in Pusat Sains Negara. 

Topics:

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. 

Ingredients: 

• 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.