6 liters
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Use the variable x to represent the volume of the 15% solution needed.
Define the total volume of the final solution:
Set up the equation based on the final concentration:
- 0.15x + 0.09(12) = 0.11(12 + x)
Expand and simplify the equation:
- 0.15x + 1.08 = 1.32 + 0.11x
Isolate x:
- 0.15x - 0.11x = 1.32 - 1.08
- 0.04x = 0.24
Solve for x:
Therefore, the chemist needs to add 6 liters of the 15% sulfuric acid solution.