Question 188875
how much pure acid should be mix with 2 gallonsof 40% acid solution in order to get a 70%acid solution.
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2 gals of 40% has 0.8 gals of acid and 1.2 gals of water.
If acid is added to be 70%, then the 1.2 gals of water will be 30% of the solution.
If 1.2 gals is 0.3 of the solution, then the total is 4 gallons.  Add 2 gallons to make it 70%.