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CH3041
ALKALINITY IV
• pH and pOH are intensity
factors :
pH = - log10[H+] pOH = - log10[OH-]
pH = - log10[H+] pOH = - log10[OH-]
• Alkalinity is a capacity factor
[alk] = [HCO3-] + 2[CO32-] + [OH-] - [H+]
(the 2 is because 1CO32- neutralises 2H+)
[alk] = [HCO3-] + 2[CO32-] + [OH-] - [H+]
(the 2 is because 1CO32- neutralises 2H+)
• eg. NaOH
1.00x 10-3 M pH = 11 (very
basic)
pH
= -log10[H+] = 14 - pOH
neutralizes 1.00x 10-3 M HCl low
alkalinity
NaHCO3 0.100
M pH = 8.34 (basic)
HCO3- + H2O D H2CO3 + OH-
HCO3- + HCl ® H2CO3 + Cl-
neutralizes
0.100 M of HCl high alkalinity
