SOLUTION: A chemist needs to have a 70% acid solution. He has 5 gallons of a 90% acid solution. How much pure water must be added to the 90% acid solution to obtain the 70% acid solution he

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Question 193595: A chemist needs to have a 70% acid solution. He has 5 gallons of a 90% acid solution. How much pure water must be added to the 90% acid solution to obtain the 70% acid solution he requires?
Found 2 solutions by Alan3354, stanbon:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
A chemist needs to have a 70% acid solution. He has 5 gallons of a 90% acid solution. How much pure water must be added to the 90% acid solution to obtain the 70% acid solution he requires?
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5 gal of 90% --> 4.5 gals of acid (the rest water)
For the 4.5 gal of acid to be 70% of the solution, the total amount of liquid is 4.5/0.7 = 45/7
5 gals is 35/7 so 10/7 gallons of water has to be added.

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A chemist needs to have a 70% acid solution. He has 5 gallons of a 90% acid solution. How much pure water must be added to the 90% acid solution to obtain the 70% acid solution he requires?
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acid + acid = acid
0.9*5 + 0*x = 0.7(x + 5)
4.5 + 0 = 07x + 3.5
0.07x = 1
x = 100/7 gallons
x = 14.29 gallons (amt. of pure water that must be added to the mixture)
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Cheers,
Stan H.