Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Zohaib on April 19, 2007, 04:26:45 PM

Title: M1V1=M2V2
Post by: Zohaib on April 19, 2007, 04:26:45 PM

Alright, well i wanted to know how you find v2 if you have everything else, like in the problem

How much water must be added to 500 ml of .200 m hcl to produce a .150 m solution ? (Assume the volumes are additive).

Title: Re: M1V1=M2V2
Post by: Yggdrasil on April 19, 2007, 04:36:20 PM

You should use the M1V1 = M2V2 formula that you have posted in the title.  From basic algebra, you can rearrange the equation (divide both sides by M2) to get:

V2 = M1V1/M2

Title: Re: M1V1=M2V2
Post by: Zohaib on April 19, 2007, 04:40:08 PM

Thanks for some reason, i always seem to confuse the division part although its very basic i often confuse m1 with m2 or so Thanks for the help.

Title: Re: M1V1=M2V2
Post by: Yggdrasil on April 19, 2007, 04:47:12 PM

Since it's easy to mix up M1 with M2 and V1 with V2, always make sure to check that the numbers you get make sense.  For example, if you are making a dilution of concentration M2 from a stock of concentration M1, then M1 > M2 and V1 < V2.

Title: Re: M1V1=M2V2
Post by: Borek on April 19, 2007, 05:46:47 PM

This tool doesn't assume volume additivity ;)

Although for such diluted solutions it doesn't matter much.

Sm stands for solution mass, other things should be obvious.

Title: Re: M1V1=M2V2
Post by: bjraines on April 19, 2007, 06:24:06 PM

Just a personal note.

I have found it easier to think of the equqation as M_initialV_initial = M_finalV_final

even thought its the same thing, my students seemed to understand it better.