How much Ca(OH)2 was added for changing pH

[MichaelZ20]

I have a composition of a solution (including pH) that was received at changing pH from 5 to 7 by Ca(OH)2 addition.
Is it possible to restore the initial composition and a mass of Ca(OH)2 added?
Will it be true to fix pH at 5 removing Ca(OH)2?

[dlparkhurst]

Something like the last calculation of this script? It should approximate the original pH 5 solution, depending on the reliability of the pH. I'm also not sure about the role of CO2; depending on the original solution, some of the pH rise to 7 could be due to CO2 degassing.

Code: [Select]

PHASES
Fix_H+
H+ = H+
log_k 0
END
SOLUTION 1
pH 5
Cl 1 charge
END
USE solution 1
EQUILIBRIUM_PHASES 1
Fix_H+ -7 Ca(OH)2 1
SAVE solution 2
END
USE solution 2
EQUILIBRIUM_PHASES 1
Fix_H+ -5 Ca(OH)2 1
END



[MichaelZ20]

Thank you!