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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: knowlewj01 on June 21, 2011, 02:43:21 PM

Title: Diluting a mixture of two components
Post by: knowlewj01 on June 21, 2011, 02:43:21 PM

Hi, sorry if this post is in the worg section, I have a quick question about calculating the Molarity of mixtures. I am doing an expriment which requires me to mix two components of 1M stock concentration and dilute them to yield 40ml samples. one of the components must be 5 micro-molar and the other varies from 0 to 50 micro-molar. Take, for example:

Component 1: Stock conc = 1M, required final conc = 5 micromolar

Component 2: Stock conc = 1M, required final conc = 25 micromolar

required final volume of mixture after dilution = 40ml.

Is there some formula i can use to work out the volume of each component i need (1,2 and diluting medium)to achieve this?

Thanks.

Title: Re: Diluting a mixture of two components
Post by: enahs on June 21, 2011, 03:14:30 PM

http://www.chembuddy.com/?left=concentration&right=dilution-mixing

Title: Re: Diluting a mixture of two components
Post by: knowlewj01 on June 21, 2011, 03:19:21 PM

that is simple, thanks *facepalm* :)

Title: Re: Diluting a mixture of two components
Post by: knowlewj01 on June 21, 2011, 03:47:14 PM

if i have 1molar stock conc of components 1 and 2 and i need the final mixture to have 5 micromolar component 1 and 25 micromolar component 2, where in that formula do the final concentrations go?

C1 V1 + C2 V2 = CF VF

what would CF be?

if C1 and C2 are both 1 Molar, where do the other concentrations come into it?

Title: Re: Diluting a mixture of two components
Post by: sjb on June 21, 2011, 03:56:04 PM

Quote from: knowlewj01 on June 21, 2011, 03:47:14 PM

if i have 1molar stock conc of components 1 and 2 and i need the final mixture to have 5 micromolar component 1 and 25 micromolar component 2, where in that formula do the final concentrations go?

C1 V1 + C2 V2 = CF VF

what would CF be?

if C1 and C2 are both 1 Molar, where do the other concentrations come into it?

How many moles would there be in a 5 micromolar solution, of volume 40ml? What volume of a 1M solution contains that number of moles?

Title: Re: Diluting a mixture of two components
Post by: enahs on June 21, 2011, 04:07:15 PM

Quote from: sjb on June 21, 2011, 03:56:04 PM

Quote from: knowlewj01 on June 21, 2011, 03:47:14 PM

if i have 1molar stock conc of components 1 and 2 and i need the final mixture to have 5 micromolar component 1 and 25 micromolar component 2, where in that formula do the final concentrations go?

C1 V1 + C2 V2 = CF VF

what would CF be?

if C1 and C2 are both 1 Molar, where do the other concentrations come into it?

Use the simple C1V1 = C2V2

You know C2 and V2 (lets just call it C_initial and C_final, 2 = final).
So, you know C1 and C2 and V2, solve for V1

They have to be in the same units though. So convert one of your concentration units.

Title: Re: Diluting a mixture of two components
Post by: knowlewj01 on June 21, 2011, 04:16:43 PM

# of moles of solute = molarity * volume
= 5E-6 * 0.04
=0.2 micro-moles

in 1 molar solution this would be 0.2E-6 of a litre.. so 0.2 micro-litres.

then the other component should be 5 times this.. so that would be 1 micro litre.

this right?