# Homework Help: Sedimentation coefficient

1. Nov 16, 2009

### quietviolence

1. The problem statement, all variables and given/known data
Escherichia coli data:
molecular weight = 74000g/mol
specific volume = 0.737cm3/g
temperature = 293 K

In a dilute aqueous buffer (0.02M potassium phosphate) at 293.75 K
speed of rotation = 56050 rpm

gave the following results:

Time (min)....x1/2
0..................5.9
20................6
40................6.1
60................6.2
80................6.3
100..............6.4
120............. 6.5
140..............6.6

2. Relevant equations
This is the equation given to us:

M=(RTs)/(D(1-($$\rho$$ f *V o))

3. The attempt at a solution
I used an R value of 8.31m2kgmol-1s-2K-1

I rearranged the equation to equal s

However, I got stuck at $$\rho$$f*Vo. Using the $$\rho$$ and V given in the question results in a division by 0.

Could someone explain to me how I find $$\rho$$ f and V o? I don't need anyone to solve the question, I would like to do that on my own.