Simultaneously prepare two of the following solutions Obtain the mass of an aspi
ID: 909073 • Letter: S
Question
Simultaneously prepare two of the following solutions
Obtain the mass of an aspirin tablet and add it to an Erlenmeyer flask.
Using a 50mL volumetric pipette, add 50.00mL of NaOH to the tablet in the flask.
Heat the flasks in a hot water bath (near boiling) for 5 minutes. (big beaker with water in it). While you are wating standardize the HCl.
calculate the moles and mass of acetylsalicylic acid in each tablet (molar mass = 180.16 g/mol)
Aspirin Tablet 0.355grams
Initial Volume 11.5mL
Final Volume 22.8mL
NaOH 0.0962 M
HCl 0.11M
Its telling me to use this formula;
Moles of HCl titrant = Excess Moles of NaOH analyte in solution
(Moles NaOH added to acetylsalicylic acid) – (Excess Moles NaOH analyte in solution) = Moles NaOH reacted Moles NaOH reacted / 2 = Moles of acetylsalicylic acid
Explanation / Answer
HCl + NaOH ---> NaCl + H2O
Aspirin + 2NaOH = sodium salicylate + CH3COONa + H2O
moles of HCl used = moles of excess NaOH
moles of excess NaOH = 0.11 M x 0.0113 L = 1.243 x 10^-3 mols
Initial moles of NaOH used for aspirin solution = 0.0962 M x 0.05 L = 4.81 x 10^-3 mols
moles of NaOH reacted with aspirin = (4.81 x 10^-3 - 1.243 x 10^-3)/2 = 1.7835 x 10^-3 mols
1 mole of NaOH reacts with 2 mole of aspirin
moles of aspirin = 1.7835 x 10^-3 mols
mass of Aspirin = moles x molar mass = 1.7835 x 10^-3 x 180.16 = 0.3213 g
So we have 0.3213 g of aspirin in the original tablet.