SOLUTION: Hi
Sorry but I made a misread my previous question. The question should be as follows; There is 500g of an 8 percent salt solution. In order to make the concentration of this s
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Sorry but I made a misread my previous question. The question should be as follows; There is 500g of an 8 percent salt solution. In order to make the concentration of this s
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Question 1148988: Hi
Sorry but I made a misread my previous question. The question should be as follows; There is 500g of an 8 percent salt solution. In order to make the concentration of this saline solution 10 percent, how many grams of water need to be evaporated.
Thanks Answer by ikleyn(52921) (Show Source):
It can be explained on an intuitive level or solved using Algebra.
First I place an intuitive explanation.
500 grams of the 8% salt solution (mass-to-mass concentration) contain 500*0.08 = 40 grams of dissolved salt.
You want to have 10% salt solution. It means that with 40 grams of salt, the total mass of the 10% solution should be 400 grams.
Hence, 100 grams of water = 500 g -400 g should be evaporated. ANSWER
Thus the intuitive explanation is just completed.
The formal algebra solution is as follows.
Again, 500 grams of the 8% solution contain 500*0.08 = 40 grams of dissolved salt.
When you evaporate water, the mass of the dissolved salt remains with no change.
Let "W" be the mass (in grams) of the water to evaporate. Then the equation for the 10% concentration is
= 0.1.
Solve it step by step. First step is to cross-multiply
40 = 0.1*(500-W)
40 = 50 - 0.W
0.1W = 50 - 40
0.1W = 10
W = 10/0.1 = 100.
ANSWER. The mass of water to evaporate is 100 grams.
Notice you got the same answer.
