Question

You have been provided 100mL of a 1000ug/ml barium standard what volume of this standard must be diluted into 50mL of ID water to produce a 30 ug/ml standard ? if you given a full 100mL of the same standard provied calculate the amount of standard and final volume required to produce a series of standards at these concentration 1 ppm,3ppm,10ppm,25ppm,50ppm and 100ppm. You will need at least 10mL of each standard and you should aviod generating any extra waste then necessary you have a 1ml pipette with 0.1mL divisiond ,a5mL pipette with 1mL divisions and 10mL class A pipette

Answer 1

I usually do too much work to do these dilution problems but I go about it this way. The first one.
1000 ug/mL x 100 mL = 100,000 ug in the 100 mL flask.
We want 30 ug/mL x 50 mL = 1500 ug in the 50 mL flask.

(100,000/100 mL) x ? = 1500 and
? = 1500 x 100/100,000 = 1.5 mL. To see if that will produce a solution that is 30 ug/mL we check it.
(100,000 ug/100 mL) x 1.5 mL = 1500 ug an
1500 ug in 50 mL = 1500 ug/50 mL = 30 ug/mL.
You can do the others.