SOLUTION: Four hundred grams of an acid solution which is 10 percent pure acid should be diluted by water. How much water must you add to reduce the strength of the solution to 8 percent pur

Question 823041: Four hundred grams of an acid solution which is 10 percent pure acid should be diluted by water. How much water must you add to reduce the strength of the solution to 8 percent pure acid?
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
Add diluent to go from 10% to 8%...
400 grams of 10% solution,
Want 8%; how much water to add?

You will note the 4 to 5 ratio of the 10% to the 8%, and the "4" part is for the 10% acid solution. Think how this proportion would work. The amount of mass of the solution will be times the 400 grams of the 10% acid. This means, 500 grams of the resulting 8% solution, an addition of 100 grams of water.

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THIS COULD ALSO BE DONE USING STRAIGHTFORWARD ALGEBRA to setup the proportions. If you feel more comfortable this way, then you could use:
Let w = grams of water to add.

, fill in the units as fit if you need them,
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