SOLUTION: A tank containing liquid is filled with 40L of 70% salt solution. What volume of the solution to be taken and be filled up with 10L of water to make the concentration 50% salt solu
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Question 1147692: A tank containing liquid is filled with 40L of 70% salt solution. What volume of the solution to be taken and be filled up with 10L of water to make the concentration 50% salt solution? Answer by ikleyn(52803) (Show Source):
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A tank containing liquid is filled with 40L of 70% salt solution. What volume of the solution to be taken
and be filled up with 10L of water to make the concentration 50% salt solution?
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The maximum possible concentration of salt in water is about 28%.
Then saturation occurs, and no more salt dissolves in water.
See this Wikipedia article https://en.wikipedia.org/wiki/Saline_water
If to forget (to neglect) this saturation effect, then the problem can be solved in this way :
Let W be the volume (in liters) of the 70% salt solution to take it off.
After taking off W liters of the 70% solution, you have (40-W) liters of the 70% solution, and you add 10 liters of water.
So, you have THIS "concentration" equation
= 0.5.
It is your basic equation for the problem.
Simplify and solve for W.
0.7*(40-W) = 0.5*(50-W)
0.7*40 - 0.7W = 0.5*50 - 0.5W
0.7*40 - 0.5*50 = 0.7W - 0.5W
28 - 25 = 0.2W
3 = 0.2W
W = = 15.
ANSWER. 15 liters of the 70% solution should be taken off and then 10 liters of water added.
