SOLUTION: How much water must be added to a bottle of 840cm cubes of acid which contains 10% of pure acid to ontain a solution containing 7% of pure acid?
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-> SOLUTION: How much water must be added to a bottle of 840cm cubes of acid which contains 10% of pure acid to ontain a solution containing 7% of pure acid?
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Question 1110771: How much water must be added to a bottle of 840cm cubes of acid which contains 10% of pure acid to ontain a solution containing 7% of pure acid?
Thank u Found 2 solutions by ikleyn, greenestamps:Answer by ikleyn(52805) (Show Source):
Your equation is
= 0.07.
It says that the ratio of the acid content to the total liquid volume (after adding x cm^3 of water) is equal to the given concentration 0.07 = 7%.
To solve the equation, multiply both sides by (840+x). It is your first step.
You will find there ALL TYPICAL mixture problems with different methods of solutions,
explained at different levels of detalization, from very detailed to very short.
Read them and become an expert in solution mixture word problems.
Since what is being added is pure water, I would use mental arithmetic to solve this problem.
(1) The amount of acid is 10% of 840 cm^3, or 84 cm^3.
(2) If that same 84 cm^3 of acid is to be 7% of the final mixture, then the total volume of the final mixture must be 84/.07 = 1200 cm^3.
(3) You started with 840 cm^3 of solution and finished with 1200 cm^3; the amount of pure water you added was 1200=840 = 360 cm^3.
