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. 

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.