Register to reply

Measuring the size of a molecule

by ecy5maa
Tags: measuring, molecule, size
Share this thread:
ecy5maa
#1
May17-11, 07:23 AM
P: 30
Hi,

1. The problem statement, all variables and given/known data
I am trying to determine the size of a molecule..by doing the oil drop experiment where we drop a tiny droplet of oil on water covered with a thin layer of powder...and then make calculations based on the diameter of the circle... the droplet forms in oil.

3. The attempt at a solution
However, the oil droplet for me is not making a circle..rather is spreading out irregularly. How can I fix this.

Everything i have used is according to this site:
http://www.practicalphysics.org/go/Experiment_633.html
but i have used talcum powder instead of lycopodeum powder
Phys.Org News Partner Science news on Phys.org
Security CTO to detail Android Fake ID flaw at Black Hat
Huge waves measured for first time in Arctic Ocean
Mysterious molecules in space
Delphi51
#2
May17-11, 04:45 PM
HW Helper
P: 3,394
I never saw a circular oil patch when my students did this experiment.
An irregular size is not much of a problem because the whole experiment is more of an estimate than a measurement. Just estimate the area of the oil patch. You can make a very good estimate if you make a grid of square cm on a transparency and hold it over the patch. A nice touch is to estimate the minimum and maximum possible area. Use a number midway between these as your "best" value, but also work out the size of a molecule using the low and the high. Then you will have not only a "best" answer but a known accuracy range.


Register to reply

Related Discussions
Measuring effect size in regressio: std coefficients, partial r2, partial correlation Set Theory, Logic, Probability, Statistics 0
Molecule size of water and oxygen General Physics 3
Effect of a magnetic field on the physical size of a paramagnetic molecule Atomic, Solid State, Comp. Physics 1
Size change in a paramagnetic molecule (oxygen) in a megnetic field? Biology, Chemistry & Other Homework 0
Experimental methods for measuring the size of nuclei High Energy, Nuclear, Particle Physics 1