What will be the pH of a solution formed by mixing 10 mL 0.1 M $N a H_{2} P O_{4}$ and 15 mL 0.1 M $N a_{2} H P O_{4}$ ?

[Given: for $H_{3} {PO}_{4}$ $p K_{a_{1}} = 2.12, p K_{a_{2}} = 7.2$ ]

Question

What will be the pH of a solution formed by mixing 10 mL 0.1 M N a H 2 P O 4 and 15 mL 0.1 M N a 2 H P O 4 ? [Given: for H 3 PO 4 p K a 1 = 2.12 , p K a 2 = 7.2 ]

TestHub · Accepted Answer

p H = p K a + log ⁡ c o n j u g a t e base a c i d Number of moles of N a H 2 P O 4 = 10 1000 L × 0.1 m o l L - 1 = 0.001 moles Number of moles of N a 2 H P O 4 = 15 1000 × L × 0.1 mol L - 1 = 0.0015 moles p H = 7.2 + log ⁡ 0.0015 0.001 = 7.37 ≈ 7.4

Chemistry - Ionic Equilibrium Question with Solution | TestHub

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