How Do You Calculate Sedimentation Coefficient for Escherichia coli?

[quietviolence]

Homework Statement

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)...x_1/2
0.....5.9
20...6
40...6.1
60...6.2
80...6.3
100.....6.4
120.... 6.5
140.....6.6

Homework Equations

This is the equation given to us:

M=(RTs)/(D(1-($$\rho$$ _f *V _o))

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*V_o. 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.

 

[Jhero]

I just need some guidance on how to find these values. Thank you!

Hi there! It looks like you're on the right track with your attempt at a solution. In order to find the values for \rho f and V o, you will need to use the given molecular weight and specific volume for Escherichia coli. These values represent the density and volume of the bacteria, respectively.

To find \rho f, you will need to convert the given specific volume from cm3/g to m3/kg. This can be done by dividing 0.737cm3/g by 1000 to get the volume in m3, and then dividing that by the molecular weight of Escherichia coli (74000g/mol) to get the volume per kg of bacteria.

To find V o, you will need to use the specific volume and the density of the buffer solution. The density of the buffer solution can be found using its molarity and the molar mass of potassium phosphate. Once you have the density, you can use it with the given specific volume to calculate the volume of the buffer solution per kg of bacteria.

I hope this helps! Keep going with your solution and let me know if you have any further questions. Good luck!