Question

20.0mls of a bulk solution was transferred to a 100ml volumetric flask and diluted to volume with water. 2.00mls of this solution was then found to have a concentration of 0.15M. What is the concentration of the bulk solution.
McVc=MdVd
(Mc)(.02L)=.15M(.002L)
Mc= .015M concentration of bulk solution

Answer 1

well since its a solution, don't all the particles mix? in which case every sample, will have a concentration of .15?

sorry if im wrong i barely passed basic chem, i suck.

Answer 2

20.0mls of a <b>bulk</b> solution was transferred to a 100ml volumetric flask and diluted to volume with water. 2.00mls of this solution was then found to have a <i>concentration</i> of 0.15M<b>/l</b>. What is the concentration of the <b>bulk</b> solution.

The bulk solution has been diluted from 20 ml to 100 ml, namely 5 times.
The diluted solution was found to have a concentration of 0.15 M/l. Thus the bulk solution has a concentration 5 times higher, namely 0.75 M/l.