Part B
For 250.0 mL of a buffer solution that is 0.210 M in HCHO2 and 0.290 M in KCHO2, calculate the initial pH and the final pH after adding 0.025 mol of NaOH. (K?(HCHO2) = 1.8 × 10??.)
Express your answers to two decimal places. Enter your answers numerically separated by a comma.
pHinitial, pHfinal = 3.88,3.98
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To find the initial pH of a buffer solution, use the Henderson-Hasselbalch equation,
$\text{pH} = \text{pK}_a + \log\frac{[\text{base}]}{[\text{acid}]}$
where [base] and [acid] are the concentrations of the conjugate base and acid, respectively. Then, to find the pH of the final solution, calculate the numbers of moles of HCHO2 and CHO2?
after the addition of NaOH. There will be 0.025 fewer moles of the acid and 0.025 more moles of the base after addition of the strong base. Substitute these values into the Henderson-
Hasselbalch equation.
Part C
For 250.0 mL of a buffer solution that is 0.265 M in CH3CH2NH2 and 0.195 M in CH3CH2NH3Cl, calculate the initial pH and the final pH after adding 0.025 mol of NaOH. (
Kb (CH3CH2NH2) = 5.6 × 10??.)
Express your answers to two decimal places. Enter your answers numerically separated by a comma.
