Question

1. Indicate what the following would do to your results: a) When measuring the acetylsalicylic acid solid, some was not transferred to the volumetric flask. b) When transferring the Aspirin Standard solution to the other solutions for dilutions, some of the liquid was not put in the volumetric flask. c) When the solutions were diluted, they were not thoroughly mixed prior measuring the transmittance. d) Instead of using iron (III) chloride as a blank when calibrating the spectrophotometer, distilled water was used. e) When preparing the cuvettes with the samples, the fingerprints of the preparer were not cleaned off.

Answer 1

a) molarity soley depends onthe concentration of solute and the volume taken..since moles of slute = weight taken/ molecular weight of compound

If we were nor able to transfer the ecact amount, then the molarity of solution will not as expected.

b) since in thsi case the a knwn concentration of the solute is diluted and then transfering was going on , if the the exact amout of the dissolved compund is transfered into the volumetric flask , then we are doing it rightly! but if some samount is left to be transfered theesulting solution will have less ilarity than expected.

c) when we dilute any solution, they are to be thoroughly shaken , because when we add the solvent ... the solute may not be able to distribute itself uniformly thoughout the solvent and thus will not be a homogenous solution. and will give differebt readings.

d)

since Fe(iii) chloride has some colour , thsiu means it will have a distinct absorbtion and we and when we don't take it as blnak , all the corresponding corresponding spectrophometer/ photometer will not be standardised according to the Fe(ii) chloride soltion . because we take the blank as zero absorbtion for these instruments.

e)

asbsorbtion depends on the path lenght and the concentration of solute.we we have fingerprints on the cuvettes then the path length will be changed, (refrative index of the resulting glass wil increase). and we will have incorrect reading!