Why Do Heavier Particles Float in a Colloidal System?

[fifi olu]

Hi,

Sorry for double posting but I wasn't sure of the right thread.

I am working with a colloidal system in which the particles are heavier than liquid. However when I add styrofoam to the system, the particles float. I can't seem to understand why the heavier particles float instead of sediment. Please help.
Thank you.

 

[davenn]

hi there
welcome to PF :)

you need to explain/clarify your experiment a bit more

what is the liquid ?
what is the denser material?
However when I add styrofoam to the system, the particles float <---- what do you mean by this ?

Dave

 

[fifi olu]

hi there
welcome to PF :)

you need to explain/clarify your experiment a bit more

what is the liquid ?
what is the denser material?
However when I add styrofoam to the system, the particles float <---- what do you mean by this ?

Dave

Hi Dave, thank you very much for your response.

the liquid is 2M hydrobromic acid (density: 1.49g/cm3)
the denser material is silica (density: 2.65g/cm3)
the sililca is dispersed in the acid. but when I add styrofoam balls to the mixture, the dispersion separates into 'acid at the bottom' and 'styrofoam with silica at the top'.

thank you again.

fifi

 

[M Quack]

I guess you answered your own question: Styrofoam with silica

The silica must bond with the styrofoam, and the resulting compound particles have a smaller density than the acid. Note that in soft condensed matter the bond can be "soft", such as electrostatic, ...

 

[fifi olu]

https://www.physicsforums.com/threads/denser-material-floats.772393/reply?quote=4861154hank you very much M Quack. I thought as much; I just doubted myself.