SOLUTION: What quantity of pure acid must be added to 500 mL of a 25% acid solution to produce a 75% acid solution?

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Question 555010: What quantity of pure acid must be added to 500 mL of a 25% acid solution to produce a 75% acid solution?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
let +x+ = ml of pure acid needed
+.25%2A500+=+125+ ml of pure acid in 25% solution
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+%28+x+%2B+125+%29+%2F+%28+x+%2B+500+%29+=+.75+
+x+%2B+125+=+.75%2A%28+x+%2B+500+%29+
+x+%2B+125+=+.75x+%2B+375+
+.25x+=+375+-+125+
+.25x+=+250+
+x+=+1000+
1,000 ml of pure acid must be added
check answer:
+%28+1000+%2B+125+%29+%2F+%28+1000+%2B+500+%29+=+.75+
+1125+%2F+1500+=+.75+
+1125+=+.75%2A1500+
+1125+=+1125+
OK