# Diffusion of particles in batch reactors

Hello everybody, I dont know if this is the right place to post this question. Sorry for that.

I have the following system: small particles (I dont know exactly the composition) in a batch stilled tank reactor in which i add some hydrochloric acid.
How I evaluate the concentration of saturation of those particles into the bulk?
I am able to calculate the loss in volume vs time considering the total volume.
I practice if we consider the solid particles as "A" and "Ca" the concentration of A, then I want to evaluate [Ca(saturation)-Ca(at a time t)] i am able to calculate Ca(at a time t) but i am not sure about Ca(saturation).
I was thinking to consider Ca(saturation) as the concentration of all A dissolved into the bulk but I am not sure about it.

Thanks very much, you can also write me at: [email protected]

siddharth
Homework Helper
Gold Member
Have you tried using the value of the solubility product of the ion A in water, to calculate the saturation concentration?

Also, what is the HCl supposed to do? Does it react with the solid particles, or with whatever diffuses out from the solid?

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diffusion of solid particles

Hello and thank you for answering,
my solid is suppose to be some kind of limestone CaCO3, it reacts with HCl and releases Ca++ ions. In literature there are data on the concentration of saturation of Ca++ in water, but the value is too small because if i measure sperimentally the mass of solid lost and convert it to moles/liter, the moles of Ca++ should be much more. For this reason there is some other solid (impurities) that react with HCl or just dissolve into the water but in the mathematical model i dont know what concentration of saturation of Ca++ i should consider because in the mathematical model [Ca(saturation)-Ca(at time t)] must be positive.
Is that completely wrong to consider the saturation for that system as the total moles of samples dissolved? The amount of acid I put into the reactor should be sufficient to dissolve all the Ca++, HCl is in a bit excess.
Thanks again.
Dino