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Chanz2104
Chanz2104
15.04.2020 • 
Chemistry

The spectrophotometer was used to measure the abosrbance of each of a series of [FeSal] solutions. A standard curve was constructed by plotting the absorbance vs. concentration (M). The slope and y-intercept were found to be 1514 M-1 and 0.002, respectively.
An aspirin sample was prepared, following the procedure given in the experiment: hydrolyzing 0.139g of it with 5ml of 1 M NaOH (reaction 1), diluting this mixture to 50.00ml (forming solution A), and taking a 1.00ml aliquot of this solution and diluting it to 50.00ml with 0.02 M Fe (III)(forming solution B- reaction 2). The absorbance of solution B was measured to be 0.351.

(a) Use the measured absorbance and the standard curve’s slope and y-intercept to calculate the concentration of [FeSal]+ in solution B.

(b) How many moles of [FeSal] were in the 50.00ml of solution B?

(c) How many moles of sodium salicylate were in the 1.00 ml aliquot of solution A used to prepare solution B? (Hint: look at the stoichiometry of reaction 2 in the experiment to see how the moles of sodium salicylate relate to the moles of [FeSal]+.

(d) Given the number of moles of sodium salicylate in 1.00 ml of solution A (calculated above), how many moles of are in the 50.00 ml of solution A? (Hint: this is not a dilution or Beer’s Law problem. It is simple multiplication)

(e) Based upon the number of moles of sodium salicylate calculated in part (d), how many moles of acetylsalicylic acid, C9H8O4, were in the sample? (Hint: look at the stoichiometry reaction (1) in the expt.).

(f) Use the mass of the aspirin sample (given in procedure section above) and the answer to part.

(e) convert to grams to calculate the mass percent of acetylsalicylic acid, C9H8O4, in the aspirin sample.

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