SOLUTION: 1)How many liters of pure acid must be added to 40 L of a 20% acid solution to make a solution which is 36% acid? 2)A laboratory technician has a solution that is 25% acid. He w

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Question 158793: 1)How many liters of pure acid must be added to 40 L of a 20% acid solution to make a solution which is 36% acid?
2)A laboratory technician has a solution that is 25% acid. He wishes to increase the concentration to 40% by adding pure acid. If he has 800 mL of solution to begin with, how much acid must be added to make the desired concentration?

Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
x+.2*40=.36(40+x)
x+8=14.4+.36x
x-.36x=14.4-8
.64x=6.4
x=6.4/.64
x=10 liters of pur acid is needed.
Proof:
10+.2*40=.36(40+10)
10+8=.36*50
18=18
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.25*800+x=.4(800+x)
200+x=320+.4x
x-.4x=320-200
.6x=120
x=120/.6
x=200 ml of pure acid is needed.
Proof:
.25*800+200=.4(800+200)
200+200=.4(1,000)
400=400