## Not an Alligation ?

by Sharon

(Missouri)

How many mL of water should be added to 2500mL of 83% (v/v)alcohol to prepare 50% (v/v) alcohol?

**Reply (by Keith)**

Although you technically could use an alligation grid to work this problem, it would be a disaster and probably take up a whole sheet of paper. Alligations are best used when you have a higher and lower concentration and know what your desired volume is, which is what's missing here.

So, a better way to do this is with basic algebra, using the formula C1V1=C2V2. You can do this one in about 6 lines on paper. Here's your first line:

**(2500)(.83) + (X)(.00) = (2500+X)(.50)**

Solve for X

**@ @ @ @ @ @ @ @ @ @ @ @ @ @ **

If you can spare 12 minutes,

watch this brief tutorial

I posted to YouTube

on Basic Algebra.**
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