A stream flows at a rate of 5.00 × 104 liters per second (L/ s) upstream of a manufacturing plant. The plant dis-charges 3.50 × 103 L/ s of water that contains 65.0 ppm HCl into the stream. (See Exercise 27 for definitions.)
a. Calculate the stream’s total flow rate downstream from this plant.
b. Calculate the concentration of HCl in ppm down-stream from this plant.
c. Further downstream, another manufacturing plant diverts 1.80 × 104 L/ s of water from the stream for its own use. This plant must first neutralize the acid and does so by adding lime:
CaO(s) + 2H+(aq) → Ca2+(aq) + H2O(l)
What mass of CaO is consumed in an 8.00- h work day by this plant?
d. The original stream water contained 10.2 ppm Ca2+. Although no calcium was in the waste water from the first plant, the waste water of the second plant contains Ca2+ from the neutralization process. If 90.0% of the water used by the second plant is returned to the stream, calculate the concentration of Ca2+ in ppm downstream of the second plant.

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