How Do We Calculate Different Average Diameters of Colloids?

  • Thread starter Thread starter kasse
  • Start date Start date
  • Tags Tags
    Average Colloids
Click For Summary
SUMMARY

The discussion focuses on calculating different average diameters of colloidal spherical polymer particles, specifically the surface average diameter and the volume average diameter. The surface average diameter is calculated using the formula d_s = √(Σ n_i d_i² / Σ n_i), while the volume average diameter is determined using d_v = √(Σ n_i d_i³ / Σ n_i). Given a dispersion with Np = 4•1013 particles/dm3 and a total surface area of 820 m2 in 1 dm3, participants discuss how to derive individual particle dimensions from the total surface area.

PREREQUISITES
  • Understanding of colloidal chemistry concepts
  • Familiarity with mathematical formulas for average diameter calculations
  • Knowledge of spherical geometry and surface area calculations
  • Basic skills in volume percentage calculations
NEXT STEPS
  • Research the derivation of particle diameter from surface area of spheres
  • Learn about the implications of volume percentage in colloidal dispersions
  • Study the differences between surface average and volume average measurements
  • Explore advanced colloidal stability and characterization techniques
USEFUL FOR

Researchers, chemists, and materials scientists involved in colloidal systems, as well as students studying colloidal chemistry and polymer science.

kasse
Messages
383
Reaction score
1
A dispersion of spherical polymer particles contains Np = 4•1013 particles/dm3. The total surface of the particles in 1 dm3 is Asp = 820 m2.

a) What kind of average diameter can we calculate. Calculate this average diameter.

b) If we know that the dispersion contains 60 vol% water, we can calculate another type of average diameter. Which? Find it!

a) Surface average.

[tex]\bar{d_s} = \sqrt{\frac{\Sigma n_i d_i^2}{\Sigma n_i}}[/tex]

b) Volume average.

[tex]\bar{d_s} = \sqrt{\frac{\Sigma n_i d_i^3}{\Sigma n_i}}[/tex]

I don't know how to incorporate the data into the formulas.
 
Physics news on Phys.org
Can't you just work it out by taking the surface area of a sphere and working back to get the radius?

You know the total surface area of the total particles in 1 litre, and you know how many particles there are in 1 litre, so from that you can work out the surface area of 1 particle.
 

Similar threads

Undergrad How Does Angular Diameter Distance Apply to the Last Scattering Surface?
  • · Replies 2 ·
Replies
2
Views
3K
Graduate How Do We Correctly Calculate the Distribution of Bosons Among Energy Levels?
  • · Replies 1 ·
Replies
1
Views
1K
How Is Gas Pressure Derived in the Kinetic Theory of Gases?
  • · Replies 3 ·
Replies
3
Views
2K
Graduate How Do You Calculate the Electric Potential of a Polarized Half-Cylinder?
  • · Replies 1 ·
Replies
1
Views
1K
Graduate Is Gravity Caused by the Motion of Particles in the Fabric of Space?
  • · Replies 463 ·
16
Replies
463
Views
75K