SOLUTION: How much acid must be added to 40ml of a 20% solution to increase it to a 28% solution?

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 Question 123566: How much acid must be added to 40ml of a 20% solution to increase it to a 28% solution?Answer by chitra(359)   (Show Source): You can put this solution on YOUR website! assuming 100% acid.... {100% }* x + [ 20% ]* (40 ml ) = ( 28 %) ( 40 + x ) where x = amount of acid in ml.... 40 + x = total ml of 28% solution ... convert % to decimal.... [ move decimal 2 times left on each ...] 1x + .20 * 40 = .28 ( 40 + x) x + 8 = 11.2 + .28x .72x = 3.2 ..... x = 4.44 ml