SOLUTION: A chemist has 100 liters of 30% sodium chloride solution. She intends to drain a certain number of liters and replace with a more concentrated solution. a) How much of this solu

Question 819020: A chemist has 100 liters of 30% sodium chloride solution. She intends to drain a certain number of liters and replace with a more concentrated solution.
a) How much of this solution should she drain and replace with 80% sodium chloride if she wants a 55% sodium chloride solution?
Found 4 solutions by josgarithmetic, stanbon, MathTherapy, richwmiller:
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!
NO!
Where did this problem come from?
At the dubious concentration of 30% sodium chloride, the solution cannot be made more concentrated.
Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
A chemist has 100 liters of 30% sodium chloride solution. She intends to drain a certain number of liters and replace with a more concentrated solution.
a) How much of this solution should she drain and replace with 80% sodium chloride if she wants a 55% sodium chloride solution?
---------------------
sc - sc + sc = sc
--------
0.30*100 - 0.30x + 1*x = 0.80*100
--------
Multiply thru by 100 to get::
30*100 - 30x + 100x = 80*100
70x = 50*100
---
x = 7.14 liters (amt of liquid to remove and replace.
-------------------------------
Cheers,
Stan H.
============
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

A chemist has 100 liters of 30% sodium chloride solution. She intends to drain a certain number of liters and replace with a more concentrated solution.
a) How much of this solution should she drain and replace with 80% sodium chloride if she wants a 55% sodium chloride solution?

Amount to be drained from 100 L of 30% CS, and replaced with 80% CS to get 55% SC: L
You can do the check!!
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Answer by richwmiller(17219)   (Show Source): You can put this solution on YOUR website!
0.8*100-0.8x+0.3x=0.55(100)
80+-0.5x=55
-0.5x=55-80
-0.5x=-25
x=50
check
0.8*50+0.3*50=0.55(100)
40+15=55
55=55
ok

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