Question
A titration is performed to determine the molar mass of an unknown solid monoprotic acid, with general formula HA. If 1.24 g of the acid requires 25.02 mL of a 0.500 M KOH solution to reach the end point, what is the molar mass of the acid? Report your answer with 2 decimal places, and do not include units.
Ask by Evans Warren. in the United States
Feb 04,2025
Real Tutor Solution
Tutor-Verified Answer
Answer
The molar mass of the acid is 99.12.
Solution
To determine the molar mass of the unknown monoprotic acid \( \text{HA} \), follow these steps:
1. **Calculate the moles of KOH used in the titration:**
\[
\text{Moles of KOH} = \text{Molarity} \times \text{Volume (in liters)} = 0.500\, \text{M} \times 0.02502\, \text{L} = 0.01251\, \text{mol}
\]
2. **Determine the moles of HA, since the reaction ratio is 1:1:**
\[
\text{Moles of HA} = \text{Moles of KOH} = 0.01251\, \text{mol}
\]
3. **Calculate the molar mass (M) of HA:**
\[
M = \frac{\text{Mass of HA}}{\text{Moles of HA}} = \frac{1.24\, \text{g}}{0.01251\, \text{mol}} \approx 99.12
\]
**Final Answer:**
99.12
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Simplify this solution The Deep Dive
To find the molar mass of the unknown monoprotic acid HA, we first need to calculate the number of moles of KOH used in the reaction. The volume of KOH solution is 25.02 mL, which we convert to liters: 25.02 mL = 0.02502 L. Next, we calculate the moles of KOH: Moles of KOH = Molarity × Volume = 0.500 mol/L × 0.02502 L = 0.01251 moles. Since the monoprotic acid HA reacts with KOH in a 1:1 ratio, the moles of HA will also be 0.01251 moles. Now we can calculate the molar mass of HA: Molar mass = Mass / Moles = 1.24 g / 0.01251 moles = 99.23 g/mol. So, the molar mass of the acid is 99.23.
