Multiple Choice
Find the pH of a solution that is 9.0×10⁻² M in H₂CO₃. Express your answer using two decimal places.
17. Acid and Base Equilibrium
pH of Weak Acids
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The pH of a solution containing HIO3 (Ka = 1.7 × 10⁻¹) and KIO3 is 1.00. If the molarity of HIO3 is 0.025 M, what is the molarity of KIO3?
A
0.050 M
B
0.075 M
C
0.100 M
D
0.025 M
Verified step by step guidance1
Start by understanding that HIO3 is a weak acid and KIO3 is its conjugate base. The solution is a buffer solution, and we can use the Henderson-Hasselbalch equation to find the molarity of KIO3.
The Henderson-Hasselbalch equation is: , where [A^-] is the concentration of the conjugate base (KIO3) and [HA] is the concentration of the acid (HIO3).
Calculate the pKa using the given Ka value: . Substitute Ka = 1.7 × 10⁻¹ into the equation to find pKa.
Substitute the given pH value (1.00), the calculated pKa, and the molarity of HIO3 (0.025 M) into the Henderson-Hasselbalch equation to solve for the molarity of KIO3.
Rearrange the equation to solve for [A^-] (KIO3): = pH - pKa. Then, calculate [A^-] using the antilog function.
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