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Name: Camille
Status: student
Grade: N/A
Location: OH
Country: N/A
Date: 1/14/2005

Why do white cotton socks seem to get cleaner in hot water than in cold water?

Hi Camille!

White socks, eh? Usually white socks used with tennis shoes get quite dirty. When you wash them using common soap or detergent cleaning at machine or by hand means to take off the dirt from the fabric. Mostly detergents have ingredients that are more soluble in hot water than in cold one and that make them to work better. Also the fabric itself in hot water gets more soft the thread opens letting the dirt to get loose, and the fabric gets cleaner.

All that happens with any kind of cloth not only socks.

(Dr. Mabel Rodrigues)

It is not an illusion, Camile. They really do get cleaner. Heat almost always makes cleaning more aggressive, in any setting.

I can think of three common behaviors that contribute to this:

1) increased reaction rates - (kinetics)

Heat speeds up all reactions, even those as humble as water wetting it's way along the interface between some slime and the fiber of your clothing.

2) increased dissolving abilities - (due to entropy)

Even without soap, small amounts of some greases will dissolve in water. In hot water, the amount that will dissolve can be ten times higher.

3) melting -

Some greases are low-melting waxes, and being melted makes it easier for the soapy water to penetrate, detach, and surround them. Even things that are not quite melted at least get softer.

Jim Swenson

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