experiment 10: determination of aspirin by spectroscopy

Question 1

it is on of the most extensively-used non-perception drug

Answer 1

aspirin or acetyl salicylic acid

Question 2

aspirin possesses what properties

Answer 2

analgesic
antipyretic
anti-inflammatory

Question 3

what can be aspirin be used due to its antiplatelet effect

Answer 3

prevent heart attacks, strokes and blood clots

Question 4

acetylsalicylic acid

Answer 4

C9H8O4

Question 5

how can be aspirin tablet be determined

Answer 5

an ultraviolet-visible (uv-vis) spectrophotometer

Question 6

what happens to the acetylsalicylic
acid when dilute NaOH is added

Answer 6

the acetylsalicylic acid is first converted into salicylate ions

Question 7

equation of ferric ions that produces the violet Fe-salicylate complex

Answer 7

3C7H5O3- + Fe+3 → Fe (C7H5O3)3

colorless to violet complex

Question 8

amount of analyte (concentration) in the sample is directly proportional to the amount of light absorbed (absorbance) by the solution

Answer 8

Beer-Lambert’s law

Question 9

equation of Beer-Lambert’s law

Answer 9

A = elc

A: absorbance
e: molar absorptivity in M-1cm-1
l: path length in cm
c: concentration in M

Question 10

how does the absorbance of the analyte will be obtained

Answer 10

using a uv-vis spectrophotometer at a wavelength where the Fe-salicylate complex has maximum absorption

Question 11

calibration curve
y-axis:
x-axis:

Answer 11

y-axis: absorbance
x-axis: concentration of 5 standard solution

Question 12

how will the equation of the straight line be determined

Answer 12

using linear regression
used to calculate the molarity of the unknown sample

Question 13

reagents

Answer 13

standard salicyclic acid
0.5 M NaOH
0.1M FeCl3
distilled water

Question 14

instrument

Answer 14

analytical balance
double-beam UV-Vis Spectrophotometer
electric stove
ortex mixer

Question 15

to hold samples for spectroscopic analysis

Answer 15

plastic cuvettes

Question 16

to grind up solid chemicals into fine powder and crush solids into smaller pieces

Answer 16

mortar and pestle

Question 17

how do u prepare the sample for analysis

Answer 17

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

Question 18

weigh how many grams of salicylic acid

Answer 18

0.0200g accurately
add 4mL of 0.50 M NaOH until all solids are dissolved

Question 19

what is the molarity of the stock solution for the standards

Answer 19

1.448 x 10^-4

Question 20

disposal of waste

Answer 20

down the sink in running water

Question 21

title of the experiment

Answer 21

determination of aspirin by spectrophotometry

Question 22

use what equipment to mix the solution thoroughly when recording for the absorbance

Answer 22

vortex mixer

Question 23

used to run a wavelength scan to determine the wavelength of maximum absorbance

Answer 23

UV-Vis spectrophotometer