dilution question - (Oct/03/2012 )

Example 1: Suppose you have 3 ml of a stock solution of 100 mg/ml ampicillin (= C1) and you want to make 200 ul (= C2)of solution having 25 mg/ ml (= V2). You need to know what volume (V1) of the stock to use as part of the 200 ul total volume needed.



I don't understand why 3ml is given? When I tried to do this problem I thought the V1 was 3ml. I know the formula that I am to use to solve this problem which is v1c1=v2c2.

Can someone clarify this

the "3ml" is to confuse you or to make it known that you have more than enough to make your dilution (it's not the limiting factor). v1 is what you are trying to determine.

by the way, you have your c2 and v2 reversed (c is for concentration, v is for volume).