An analytical chemist weighs out 0.057g of an unknown monoprotic acid into a 250mL volumetric flask and dilutes to the mark with distilled water. She then titrates this solution with 0.1400M NaOH solution. When the titration reaches the equivalence point, the chemist finds she has added 4.7mL of NaOH solution.Calculate the molar mass of the unknown acid. Round your answer to 2 significant digits.
Question
An analytical chemist weighs out 0.057g of an unknown monoprotic acid into a 250mL volumetric flask and dilutes to the mark with distilled water. She then titrates this solution with 0.1400M NaOH solution. When the titration reaches the equivalence point, the chemist finds she has added 4.7mL of NaOH solution.Calculate the molar mass of the unknown acid. Round your answer to 2 significant digits.
Solution
To calculate the molar mass of the unknown acid, we need to follow these steps:
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First, we need to calculate the moles of NaOH used in the titration. We can do this using the formula: moles = concentration * volume. The concentration of NaOH is given as 0.1400 M and the volume is 4.7 mL (which we need to convert to L by dividing by 1000), so the moles of NaOH is 0.1400 * 4.7/1000 = 0.000658 mol.
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Since the unknown acid is monoprotic, it means that one mole of the acid reacts with one mole of NaOH. Therefore, the moles of the unknown acid is also 0.000658 mol.
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Now we can calculate the molar mass of the unknown acid using the formula: molar mass = mass / moles. The mass of the unknown acid is given as 0.057 g and we have calculated the moles as 0.000658 mol, so the molar mass is 0.057 / 0.000658 = 86.63 g/mol.
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Rounding to two significant digits, the molar mass of the unknown acid is 87 g/mol.
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