Answer to Question #65098 in General Chemistry for naveen

Question

1. What is the unit for polarization, α, from the VDW potential energy?
2. Why is the melting point trend decreasing in methane, ethane to propane but then suddenly increasing from butane to pentadecane?
3. Why do carbon nanotubes want to bundle?

Answer 1

1) The SI unit of measure is coulombs per square meter
2) For melting point, the trend line does not appear as smooth as the boiling point trend line. This is due to an important difference between odd and even numbered carbon chains. Even numbered carbon chains pack tighter (closer) when solid, therefore requiring more energy to separate them and enter the liquid phase. Conversely, odd numbered carbon chains do not pack as tightly together in the solid phase and can be separated easier, thus making a lower melting point.
3) Please see https://web.mit.edu/mbuehler/www/SIMS/Adhesion%20of%20Carbon%20Nanotube.html