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2. A. A crude dialysate yields an absorbance reading of 12 when undiluted. What

ID: 1085109 • Letter: 2

Question

2. A. A crude dialysate yields an absorbance reading of 12 when undiluted. What dilution would be necessary to get the absorbance of 0.5? 1:24 dilution needed B. Most cuvettes hold ~1 mL total volume and must be at least ¾ full to obtain a reading. If you wish to dilute the sample above, what's a reasonable volume to use for your diluted sample? C. Using the dilution factor you determine in part (A) and final volume chosen in part (B), what volume of the crude dialysate and what volume of buffer (to dilute) would you use?

Explanation / Answer

2B)

net volume a cuvette can hold=3/4* 1ml=0.75ml

2C) dilution factor in part A)

Absorbance is directly proportional to concentration of absorbing species and so to the volume of the species

Absorbance1/Abs2=Volume1/volume2=12/0.5=24/1

dilution factor =1/24

To prepare 24 ml of diluted sample, 1ml undiluted sample is used

Thus, To prepare 0.75 ml of diluted sample, 1/24*0.75=0.0312 ml undiluted sample is used

0.0312 ml undiluted sample must be diluted to 0.75ml by adding buffer=0.75ml-0.0312ml=0.719 ml

Buffer=0.719ml

crude vol=0.0312ml