SOLUTION: how many liters of a 90% acid solution must be added to 6 liters of a 15% acid solution to obtain a 40% acid solution ?

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Question 44394: how many liters of a 90% acid solution must be added to 6 liters of a 15% acid solution to obtain a 40% acid solution ?
Answer by adamchapman(301) About Me  (Show Source):
You can put this solution on YOUR website!
Let the amount of litres of 90% acid solution be called "x".
We know the finalsolution will have a 40% acid solution and will be 6+x litres in volume.
Multiplying volumes by solutions, where the percentage of acid concentration is in decimal form (i.e. 0.5=50%):
0.9x%2B0.15%286%29=0.4%286%2Bx%29
Now rearrange to get x:
0.9x%2B0.9=2.4%2B0.4x
0.9x-0.4x=2.4-0.9
0.5x=1.5
x=1.5%2F0.5
x=3
So 3 liters of a 90% acid solution must be added to 6 liters of a 15% acid solution to obtain a 40% acid solution.



I hope this helps.
P.S. I am trying to start up my own homework help website. I would be extremely grateful if you would e-mail me some feedback on the help you received to adam.chapman@student.manchester.ac.uk