Question

This question deals with dilutions. It has four parts.

A) If the dilution of a sample is 1/8, what is the dilution factor (D.F.)? I got my answer to be 8.

B) Suppose you want to make a 1/18 dilution of a sample.
If you use 7 ml of the sample, how many ml of diluent do you need to use?
(NOTE: You do not need to put units in your answer, the units in this problem are milliliters.) I got my answer to be 119.

C) In a three step serial dilution:
the first dilution is 1/6
the second dilution is 1/2
the third dilution is 1/10

Answer 1

A) As the formula for Dilution factor is D.F=1/dil so D.F=1÷1/8 ⇒ 8. Your answer is absolutely right.

B) Stock solution = 7ml

D.F=1÷1/18⇒18

Also, D.F= Final solution volume/Volume from stock solution, So:

Final solution volume= Volume from stock solution× Dilution factor⇒7×18=126 ml

For amount of diluent= Total solution- stock solution⇒ 126-7=119.

119 ml of diluent is required to make 1/18 dilution of 7 ml stock solution.

C) If we want to know the final Dilution Factor, we will simply multiply all dilutions.

Final dilution factor will be : 1/6 x 1/2 x 1/10 = 1 : 120 or D.F= 120