Question

Hydrodyapatite is a bioceramic that goes by the formula Ca5(PO4)3(OH)(s) how would you explain that you can make it deposits on an electrode immersed in an hydroxyapatite liquid solution by applying negative potential to the electrode.
Knowing that if you make the pH go basic dissolved hydroxyapatite will go up?

Answer 1

negative potential = gives electrons. The electrons released at the electrode causes the deposition of the metal because it's reduced onto it. I dont understand the last sentence

Answer 2

Thank you and sorry I wasn't clear, what I meant was that the more the pH is basic the more hydroxyapatite will precipitate since the ionic product of HAP depends on the concentration of [OH-],
I was told that by applying potential to the electrode we would have OH- on the surface of said electrode, which would then make the hydroxyapatite deposit on it.
Why would OH- ions aggregate on the electrode when you apply negative potential?
The conditions of the experiment were the following:
The electrode is immersed in an aqueous solutions in which is dissolved Ca5(PO4)3(OH)(s)

Answer 3

so i think what i said wasn't completely correct.

I looked around the net and it shows that water is reduced at the electrode, creating \(OH^-\) ions \(2H_2O+2e^-\rightarrow 2OH^-+H_2\)

then the HA complex forms on the electrode as the hydroxide ions displace the solvent molecules (water). Roughly:

\(Ca_x(PO_4)_y(H_2O)_v+zOH^-\rightarrow Ca_x(PO_4)_y(OH)_z +vH_2O \)

Answer 4

Thanks I think I understand.