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A 0.010 M solution of a monobasic weak acid HA has ionization…

Question

A 0.010 M solution of a monobasic weak acid HA has ionization constant Ka = 1.0 x 10^-5. Without using the simplifying approximation (C - h ~ C), calculate the exact pH of the solution. Give the answer rounded to three decimal places.

✓ Verified answer: 3.507checked by our engine — not a guess

Step-by-step solution

Ka = h^2/(C - h) with C = 0.010, Ka = 1.0e-5. This gives h^2 + 1.0e-5 h - 1.0e-7 = 0. Solving: h = [-1.0e-5 + sqrt(1.0e-10 + 4.0e-7)]/2 = 3.112e-4 M. pH = -log10(3.112e-4) = 3.507. Final answer: 3.507

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