You will be using 0.2 M NaOH as your titrant solution. Your first job is to predict how many milliliters (mL) you are EXPECTING to use for the 500mg tablet. Use the molar mass of aspirin as 180.17 g/mol for ALL future calculations where molar mass is needed.
How many moles would be present in a 500 mg tablet?
Knowing that the mole ratio for the titration is 1 mol NaOH: 1 mol Asp, what volume of 0.2 M NaOH would be needed if the expected tablet is 500 mg?
The actual titration you performed used 0.0417 L of 0.2 M NaOH. How many moles of aspirin in your actual sample are present?
And finally, using your answer choice from #3, how many milligrams of aspirin was in the sample tablet from the same batch that made the person ill? [Note: If your answer from #3 is incorrect, but you do the calculation for this question correctly, I will count it as correct.]