pamp@bcsaic.UUCP (04/17/86)
In article <861@harvard.UUCP> lo@harvard.UUCP (Bert S.F. Lo) writes: >In article <615@eneevax.UUCP>, hsu@eneevax.UUCP (Dave Hsu) writes: >> In article <1178@lsuc.UUCP> dave@lsuc.UUCP (David Sherman) writes: >> > >> >I have a kind of silly little question that I've been curious >> >about for a while. Can someone explain to me the principles >> >on which dish detergent (and, I suppose, any soap) works? >> >> It's largely the bubbles. They form a film on what you're cleaning with a >> different surface tension. The soap solution works, but not as well as the >> bubbles. > >My housemate and I used to have these ridiculous arguments about doing dishes. >She would stopper the drain, put in the detergent and fill with water while I >would apply the detergent directly onto the surface, to be spread around by the >sponge. Both methods were followed up by rinsing the detergent off the dishes. >According to your explanation, her method is better. Yet, whenever she did the >dishes, the greasy dishes would fail to come clean. Is it because my method >creates a greater number of bubbles during the rinsing phase ? I'm not sure exactly why the bubbles work better on grease -- but it may have something to do with the amount of water molecules involved in both cases. Detergent breaks up organic molecules (grease,oil, pitch, even asphalt) (which are all long polymer chains) by attaching to sections with sites in its own molecule that are charged. (forgive this vague organic chem explaination -- it's been nearly 10 years since I took the course and I'm hazy on the subject...) When water molecules come into the picture, the power of a detergent to break up the organic chains is decreased because the dipolar water molecules bind to a fair amount of the active detergent sites. This leaves fewer sites for the detergent to attach to the organic (grease) chains, so the grease isn't broken up as well. (Note:What this all means is that to break up grease faster the more detergent you use and LESS water the better the grease is broken up. In fact, for really greasy dishes,pans,etc... I rub a little detergent on the pan without water, rub it around, and rinse -- no grease... squeaky clean. Works great with clothes and oil stains -- even tar! Straight detergent does wonders --- just rub it in and let it sit a bit. (I even used this method to get some tar out of my Irish Setters hair when the idiot had run across a newly paved road. Much better than trying to use kerosene...)) What might be happening with the bubbles is that less water is interfering with the detergents active sites and allowing it to get to the grease and break it up. (The action of detergent was one of the more interesting subjects that my organic chemistry prof covered in college -- he always had a great time pointing out "household tips".) Pamela M. Pincha-Wagener