General Lab Techniques - (Jul/08/2006 )

Plz can anyone tell me

Why Detergents dissolved in water form Froth on shaking ....

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With shaking you introduce air bubbles in a water/detergent mix. Detergents are molecules with hydrophobic and hydrpophile ends (remember?), and they tend to arrange in a way that the hydrophobe ends can avoid water, they form spheres. The air bubbles are now sourrounded by a relatively stable surface of water/tensid, besides the bubbles tend to get spherical and build a 3d network which is more or less stable (dependend on tensid type, temperature etc). So it is a dispersion of air in water-tensid mix and interferes with pipetting...

I'm not a physicist, but hopefully it is almost correkt...But forgot the surface tension, it is necessary that it is reduced.

hobglobin

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