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 Sep 8th 2018, 08:31 PM #1 Dierdron Junior Member   Join Date: Sep 2018 Location: Oregon Posts: 3 Stock Solution Question If I have a a 40% solution and a 95% solution, how much of each do I need to make a 70% solution with a final volume of 375 ml? My 30 credits in chemistry was too many years ago and I'm out of practice (and stuck.). I've been playing around with the stock formula and algebraically rearranging for some time. It's the constrained target volume twist that's stumping me. Last edited by Dierdron; Sep 8th 2018 at 08:36 PM.
 Sep 10th 2018, 08:09 AM #2 Woody Junior Member   Join Date: Sep 2018 Location: England Posts: 13 Perhaps more of a maths question! Simultaneous equations should do it: Let x be the volume of the 40% solution Let y be the volume of the 95% solution The total volume required is 375ml so: x+y = 375 also: 40*x+95*y = 70*375 two equations, two unknowns, You ok from here?
 Sep 12th 2018, 07:19 PM #3 Dierdron Junior Member   Join Date: Sep 2018 Location: Oregon Posts: 3 Oh yeah, systems of equations. That’s much more efficient than the trial and error I used for the actual problem. This will come in handy for future dilutions. Thank you!
Sep 12th 2018, 08:22 PM   #4
Dierdron
Junior Member

Join Date: Sep 2018
Location: Oregon
Posts: 3
Worked out

Picture attached showes problem worked out
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