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Chemistry / What determines how many bubbles form in a liquid?

« on: 11/10/2009 17:03:07 »

It's been a while since I last posted, but I hope you guys can help me out!

Does anyone have any idea on how heat or concentration or how vigorous whisking might affect the formation of bubbles in a liquid? I'm trying to make the MOST bubbles with as small a size as possible - i.e. I just want foam.

So far, I've established that very hot water prevents the small foam from forming - in fact I get really few big bubbles and almost no small bubbles this way.


[MOD EDIT - GOOD TO HAVE YOU BACK - BUT PLEASE CAN YOU ENSURE THAT YOUR THREAD TITLES ARE PHRASED AS QUESTIONS, IN LINE WITH OUR FORUM POLICY. THANKS. CHRIS]

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Physics, Astronomy & Cosmology / Does the frequency of light change when it refracts?

« on: 13/05/2009 12:23:52 »

I was just wondering...

Refractive Index, n, is defined by

n = c / v

where c is the speed of light in a vacuum, and v is the speed in the medium.

Now, since light is a wave, we look at v = fλ.

So when light refracts, it slows down but then is it the frequency that changes, the wavelength that changes or both?

3

Chemistry / Why is the Gibbs Free Energy Curve of an Equilibrium Reaction U-Shaped?

« on: 25/02/2009 08:32:05 »

I know it's totally intuitive, since the reaction proceeds towards the equilibrium state therefore it must have the most negative Gibbs Free Energy but how do we actually get the curve?

http://www.oup.com/uk/orc/bin/9780199249732/freelecturer/figures/fig8_5.tif

Source: Oxford University Press

4

Plant Sciences, Zoology & Evolution / Home-made Nutrient Solution for Plants?

« on: 21/01/2009 06:50:31 »

Hello everyone!

Recently I've been trying to make a little Aeroponics setup to grow lettuce and possibly other products in the future. Now the idea is to keep spraying water or some kind of nutrient solution onto the roots of the plant so that it continues to grow, as opposed to a hydroponics setup which keeps the roots immersed in water.

My question is, do any of you know how to make a nutrient solution for this? Thus far I have come up with the following possibilities:

Urine, Mineral Water, Tap Water and Distilled Water (Control)

I figured that they'd have a different assortment of minerals and so would affect growth differently.

5

Chemistry / What happens, on a molecular level, when a solid is cut?

« on: 29/12/2008 14:27:16 »

I was just thinking suddenly - what happens when you cut a solid on a molecular level?

Is it simply that you break bonds? If it is, why is it not possible that two solids become one solid again when you put them together at the same place you cut them?