Answer:
1) 8 liters of pure acid
2) 27 liters of 35% ethanol
3) 8.2 liters of 30% acid
Step-by-step explanation:
The inicial amount of acid is 15% of 12 L, and the inicial volume is 12L.
Adding 'x' L of 100% acid, we have the amount of acid equal to 12 * 0.15 + x * 1, and the volume of 12 + x. The concentration is the amount of acid over the volume, so we have that:
(12*0.15 + x) / (12 + x) = 49/100
(1.8 + x)*100 = (12 + x) * 49
180 + 100x = 588 + 49x
51x = 408
x = 8 liters of pure acid
Similar to the solution above, for the second question we have:
(23*0.26 + 0.35*x) / (23 + x) = 30.86/100
(5.98 + 0.35*x)*100 = (23 + x) * 30.86
598 + 35x = 709.78 + 30.86x
4.14x = 111.78
x = 27 liters of 35% ethanol
For the third question, we have:
(10*0.5366 + 0.3*x) / (10 + x) = 43/100
(5.366 + 0.3x)*100 = (10 + x)*43
536.6 + 30x = 430 + 43x
13x = 106.6
x = 8.2 liters of 30% acid
