Here's one for physical science and chemistry geeks..

1. 76

   DzyMsLizzyposted 10 years ago

   Here's one for physical science and chemistry geeks..
   
   I understand WHAT surfactants are; what they do.  What I do not know, and would like to understand, is HOW they do what they do.
   How do they break the surface tension of water; break that bond, without turning the water into a different element by the mixing of the chemical agent with the water?

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2. 76

   tsadjatkoposted 10 years ago

   
   
   A DIALOGUE WITH SARAH, AGED 3: IN WHICH IT IS SHOWN THAT IF YOUR DAD IS A CHEMISTRY PROFESSOR, ASKING “WHY” CAN BE DANGEROUS
   SARAH: Daddy, were you in the shower?
   DAD: Yes, I was in the shower.
   SARAH: Why?
   DAD: I was dirty. The shower gets me clean.
   SARAH: Why?
   DAD: Why does the shower get me clean?
   SARAH: Yes.
   DAD: Because the water washes the dirt away when I use soap.
   SARAH: Why?
   DAD: Why do I use soap?
   SARAH: Yes.
   DAD: Because the soap grabs the dirt and lets the water wash it off.
   SARAH: Why?
   DAD: Why does the soap grab the dirt?
   SARAH: Yes.
   DAD: Because soap is a surfactant.
   SARAH: Why?
   DAD: Why is soap a surfactant?
   SARAH: Yes.
   DAD: That is an EXCELLENT question. Soap is a surfactant because it forms water-soluble micelles that trap the otherwise insoluble dirt and oil particles.
   SARAH: Why?
   DAD: Why does soap form micelles?
   SARAH: Yes.
   DAD: Soap molecules are long chains with a polar, hydrophilic head and a non-polar, hydrophobic tail. Can you say ‘hydrophilic’?
   SARAH: Aidrofawwic
   DAD: And can you say ‘hydrophobic’?
   SARAH: Aidrofawwic
   DAD: Excellent! The word ‘hydrophobic’ means that it avoids water.
   SARAH: Why?
   DAD: Why does it mean that?
   SARAH: Yes.
   DAD: It’s Greek! ‘Hydro’ means water and ‘phobic’ means ‘fear of’. ‘Phobos’ is fear. So ‘hydrophobic’ means ‘afraid of water’.
   SARAH: Like a monster?
   DAD: You mean, like being afraid of a monster?
   SARAH: Yes.
   DAD: A scary monster, sure. If you were afraid of a monster, a Greek person would say you were gorgophobic.(pause)
   SARAH: (rolls her eyes) I thought we were talking about soap.
   DAD: We are talking about soap.(longish pause)
   SARAH: Why?
   DAD: Why do the molecules have a hydrophilic head and a hydrophobic tail?
   SARAH: Yes.
   DAD: Because the C-O bonds in the head are highly polar, and the C-H bonds in the tail are effectively non-polar.
   SARAH: Why?
   DAD: Because while carbon and hydrogen have almost the same electronegativity, oxygen is far more electronegative, thereby polarizing the C-O bonds.
   SARAH: Why?
   DAD: Why is oxygen more electronegative than carbon and hydrogen?
   SARAH: Yes.
   DAD: That’s complicated. There are different answers to that question, depending on the Pauling or Mulliken electronegativity scales. But it really all comes down to effective nuclear charge. The electrons in an oxygen atom have a lower energy than a carbon atom, and electrons shared between them are held more tightly to the oxygen Cool, huh?(pause)
   SARAH: I don’t get it.
   DAD: That’s OK. Neither do most of my students.

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   1. 76

      DzyMsLizzyposted 10 years agoin reply to this

      That's hilarious.  But thanks for the explanation.  I mostly get it! ;-)

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