Questions: An analytical chemist weighs out 0.051 g of an unknown monoprotic acid into a 250 mL volumetric flask and dilutes to the mark with distilled water. He then titrates this solution with 0.0600 M NaOH solution. When the titration reaches the equivalence point, the chemist finds he has added 14.2 mL of NaOH solution. Calculate the molar mass of the unknown acid. Round your answer to 2 significant digits. g/mol

An analytical chemist weighs out 0.051 g of an unknown monoprotic acid into a 250 mL volumetric flask and dilutes to the mark with distilled water. He then titrates this solution with 0.0600 M NaOH solution. When the titration reaches the equivalence point, the chemist finds he has added 14.2 mL of NaOH solution.

Calculate the molar mass of the unknown acid. Round your answer to 2 significant digits.

g/mol

Transcript text: An analytical chemist weighs out 0.051 g of an unknown monoprotic acid into a 250 mL volumetric flask and dilutes to the mark with distilled water. He then titrates this solution with 0.0600 M NaOH solution. When the titration reaches the equivalence point, the chemist finds he has added 14.2 mL of NaOH solution. Calculate the molar mass of the unknown acid. Round your answer to 2 significant digits. $\square$ $\square$ $\frac{\mathrm{g}}{\mathrm{mol}}$

Solution

Solution Steps

Step 1: Determine Moles of NaOH Used

First, calculate the number of moles of NaOH used in the titration. The volume of NaOH solution added is 14.2 mL, which is equivalent to 0.0142 L. The concentration of NaOH is 0.0600 M.

\[ \text{Moles of NaOH} = \text{Concentration} \times \text{Volume} = 0.0600 \, \text{mol/L} \times 0.0142 \, \text{L} = 0.000852 \, \text{mol} \]

Step 2: Relate Moles of NaOH to Moles of Acid

Since the acid is monoprotic, it reacts with NaOH in a 1:1 molar ratio. Therefore, the moles of the unknown acid are equal to the moles of NaOH used.

\[ \text{Moles of acid} = 0.000852 \, \text{mol} \]

Step 3: Calculate the Molar Mass of the Acid

The molar mass of the acid is calculated by dividing the mass of the acid by the moles of acid.

\[ \text{Molar mass} = \frac{\text{Mass of acid}}{\text{Moles of acid}} = \frac{0.051 \, \text{g}}{0.000852 \, \text{mol}} \approx 59.859 \, \text{g/mol} \]

Step 4: Round to Two Significant Digits

Round the molar mass to two significant digits as required.

\[ \text{Molar mass} \approx 60 \, \text{g/mol} \]