Respuesta :
The mass balance equation is 0.15 M = [H₃PO₄] + [H₂PO₄⁻] + [HPO₄²⁻] + [PO₄³⁻] and the charge balance equation is [H₃O⁺] + [K⁺] + [Na⁺] = [H₂PO₄⁻] + 2 × [HPO₄²⁻] + 3× [PO₄³⁻] + [OH⁻] for a solution containing 0.10 m KH2PO4 and 0.050 m Na2HPO4.
To find out the mass balance and the charge equation
Let's record all the reactions that result in the formation of the solutions and the equilibria that exist within them to aid in our ability to identify the ions that are there. Two soluble salts are dissolving in these reactions.
KH₂PO₄(s) → K⁺ (aq) + H₂PO₄⁻ (aq)
Na₂HPO₄ → 2Na⁺ + HPO₄²⁻
and the processes of acid-base dissociation for H₂PO₄⁻ , HPO₄²⁻ and H₂O
H₂PO₄⁻ + H2O → H3O⁺ + HPO₄²⁻
H₂PO₄- + H2O → OH⁻ + H₃PO₄
HPO₄²⁻ + H₂O → H3O⁺ + PO₄³⁻
2H2O → H₃O⁺ + OH⁻
Please take note that the base dissociation reaction for HPO4 2⁻ was left out because its byproduct, H2PO4 ⁻, was previously taken into consideration in another reaction. Simple mass balance equations exist for K+ and Na+.
[K⁺] = 0.1M [Na⁺] = 0.1M
However, the mass balance equation for phosphate requires some consideration. The same ions are produced in solution by H2PO4 and HPO4.
As a result, we can consider that the solution originally contains 0.15 M KH2PO4, which results in the mass balance equation shown below.
0.15 M = [H₃PO₄] + [H₂PO₄⁻] + [HPO₄²⁻] + [PO₄³⁻]
Hence final charge balance equation is
[H₃O⁺] + [K⁺] + [Na⁺] = [H₂PO₄⁻] + 2 × [HPO₄²⁻] + 3× [PO₄³⁻] + [OH⁻]
Learn more about Charge balance equations here https://brainly.com/question/28044744
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