Table 19 Arsenic   H3AsO4 H+ + H2AsO4- K1= 2.5 ´ 10- 4                 H2AsO4- H+ + HAsO42 - K2=5.6 ´ 10- 8                   H3AsO42 - H+ + AsO43 - K3=3 ´10- 13 Oxalic   H2C2O4 H+ + HC2O4- K1=5.9 ´ 10- 2               H2C2O4- H+ + C2O42 - K2=6.4 ´ 10- 5 Phosphoric   H3PO4 H+ + H2PO4- K1=7.5 ´ 10- 3                      H2PO4- H+ + HPO42 - K2=6.2 ´ 10- 8                      HPO42 - H+ + PO43 - K3=1 ´ 10- 12 Sulfuric   H2SO4 H+ + HSO4- K1=Strong              HSO4- H+ + SO42 - K2=1.3 ´ 10- 2

As the rate of dissociation for successive dissociating is very low [ H⁺ ] from those is (almost negligible) in comparison, hence pH of the solution is determined mainly by first dissociation (principle source of primary H⁺ ).

Consider the following equilibria to calculate ion concentrations in 0.01 m solution of H2S.

(K₁ = 1.1 ´ 10^{- 7}, K₂ = 1 ´ 10^{- 14})

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Index

12.1 - Lowry and Bronsted Concept
12.2 - Conjugate Acid Base Pairs
12.3 - Amphoteric Substance
12.4 - Lewis Acids and Bases
12.5 - Strong and Weak Acids and Bases
12.6 - Dissociation
12.7 - Ostwald's Dilution Law
12.8 - Hydrogen Ion Concentration : pH
12.9 - Polyprotic Acids
12.10 - Salts
12.11 - Methods of Preparation of Salts
12.12 - Properties of Salts

Chapter 13