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Could someone offer a pointer to whether I have the right thinking on this, please?
The way I see it, the K2CO3 would lead to bicarbonate ions, HCO3-, and hydroxides, OH-, upon water dissociation.
Now when those bicarb ions meet the H2PO4- and HPO4-- phosphate ions, I presume you could see an oxidation of the bicarbonate ions and a release of CO2?
( HCO3- + H2PO4- -> HPO4-- + H2O + CO2 )
The only thing is that with CO2 in solution, would it not re-react with the other K2CO3 and reach an equilibrium, per K2CO3 + CO2 + H2O -> 2KHCO3 ?
This would suggest K2CO3 + KH2PO4 <-> KHCO3 + K2HPO4?
Thing is, there's something in the back of my mind that makes me think not all of the CO2 would be reabsorbed by the K2CO3, so what we'd see is some escaping with a quite slow bubbling away of the CO2 that doesn't end up back in a bicarbonate. So over a non-rapid timescale, we'd see all of the CO3-- drift away, but quite slowly, and we could end up with;
K2CO3 + KH2PO4 -> K2HPO4 + KOH + CO2 (gas)
( and also that K2HPO4 + KOH <-> K3PO4 + H2O ? )
The way I see it, the K2CO3 would lead to bicarbonate ions, HCO3-, and hydroxides, OH-, upon water dissociation.
Now when those bicarb ions meet the H2PO4- and HPO4-- phosphate ions, I presume you could see an oxidation of the bicarbonate ions and a release of CO2?
( HCO3- + H2PO4- -> HPO4-- + H2O + CO2 )
The only thing is that with CO2 in solution, would it not re-react with the other K2CO3 and reach an equilibrium, per K2CO3 + CO2 + H2O -> 2KHCO3 ?
This would suggest K2CO3 + KH2PO4 <-> KHCO3 + K2HPO4?
Thing is, there's something in the back of my mind that makes me think not all of the CO2 would be reabsorbed by the K2CO3, so what we'd see is some escaping with a quite slow bubbling away of the CO2 that doesn't end up back in a bicarbonate. So over a non-rapid timescale, we'd see all of the CO3-- drift away, but quite slowly, and we could end up with;
K2CO3 + KH2PO4 -> K2HPO4 + KOH + CO2 (gas)
( and also that K2HPO4 + KOH <-> K3PO4 + H2O ? )