Easing the tension

This is the scientific follow up to the super fun bubble experiments we did on The Garage Creative. To see what we did, follow The Garage Creative.


In our house, we use a lot of soap, whether it is for washing dishes or the hands of our two little girls. Every time I use soap, I cannot help but wonder what it is about soap that causes it to lather while at the same time, kill whatever harmful bacteria it may be washing off.

First, why were we able to blow such big bubbles? If you think about water, it is "sticky", though not the way we normally think something is sticky. It holds itself to itself very well. When we fill our glass completely full, it does not pour out. We can even gently place a greasy paperclip on water and the surface tension of the water will keep it from sinking.

With water being that sticky it is difficult to stretch it to make a bubble. This is where soap comes in. Soap has properties that explain cleanliness question as well as the gigantic bubbles.

Soap is made from long chains of carbon and hydrogen atoms. One end of the chain loves water, which scientists call hydrophyllic. As you may have guessed, the other end of the chain does not like water, which scientists term hydrophobic. When we wash dishes or hands, the hydrophobic side of the chain attaches to the grease in the pan or hands and allows water to rush under it, sweeping it away!

So in reality, soap does not kill bacteria, rather it makes whatever we are washing more greasy so bacteria can be washed away. 

This is a very brief description of what happens, check out the eXploratoriums description if you would like more!