experiment 10: determination of aspirin by spectroscopy Flashcards
it is on of the most extensively-used non-perception drug
aspirin or acetyl salicylic acid
aspirin possesses what properties
analgesic
antipyretic
anti-inflammatory
what can be aspirin be used due to its antiplatelet effect
prevent heart attacks, strokes and blood clots
acetylsalicylic acid
C9H8O4
how can be aspirin tablet be determined
an ultraviolet-visible (uv-vis) spectrophotometer
what happens to the acetylsalicylic
acid when dilute NaOH is added
the acetylsalicylic acid is first converted into salicylate ions
equation of ferric ions that produces the violet Fe-salicylate complex
3C7H5O3- + Fe+3 → Fe (C7H5O3)3
colorless to violet complex
amount of analyte (concentration) in the sample is directly proportional to the amount of light absorbed (absorbance) by the solution
Beer-Lambert’s law
equation of Beer-Lambert’s law
A = elc
A: absorbance
e: molar absorptivity in M-1cm-1
l: path length in cm
c: concentration in M
how does the absorbance of the analyte will be obtained
using a uv-vis spectrophotometer at a wavelength where the Fe-salicylate complex has maximum absorption
calibration curve
y-axis:
x-axis:
y-axis: absorbance
x-axis: concentration of 5 standard solution
how will the equation of the straight line be determined
using linear regression
used to calculate the molarity of the unknown sample
reagents
standard salicyclic acid
0.5 M NaOH
0.1M FeCl3
distilled water
instrument
analytical balance
double-beam UV-Vis Spectrophotometer
electric stove
ortex mixer
to hold samples for spectroscopic analysis
plastic cuvettes
to grind up solid chemicals into fine powder and crush solids into smaller pieces
mortar and pestle
how do u prepare the sample for analysis
weigh 0.0150 to 0.0200 g of ground aspirin tablet
transfer to 100ml beaker
add 10ml of 0.50 M NaOH
heat using a hot plate until most solid dissolves
cool then transfer into volumetric flask without the solids
transfer to clean glass bottle
weigh how many grams of salicylic acid
0.0200g accurately
add 4mL of 0.50 M NaOH until all solids are dissolved
what is the molarity of the stock solution for the standards
1.448 x 10^-4
disposal of waste
down the sink in running water
title of the experiment
determination of aspirin by spectrophotometry
use what equipment to mix the solution thoroughly when recording for the absorbance
vortex mixer
used to run a wavelength scan to determine the wavelength of maximum absorbance
UV-Vis spectrophotometer
