To prepare community wastewater to be released to a lake, phosphate ions (among others) must be removed Al 2 (SO 4 ) 3 can be used for this purpose, precipitating AlPO 4 , for which K sp at 25C is 1 3 10 20 What mass of Al 2 (SO 4 ) 3 must be added per gallon of water to assure that the concentrati...

To prepare community wastewater to be released to a lake, phosphate ions (among others) must be removed.

Question:

To prepare community wastewater to be released to a lake, phosphate ions (among others) must be removed. Al₂(SO₄)₃ can be used for this purpose, precipitating AlPO₄, for which K_sp at 25°C is 1.3 × 10^–20. What mass of Al₂(SO₄)₃ must be added per gallon of water to assure that the concentration of PO₄ ^3– in the water released to the lake will be no higher than 1.0 × 10^–12 M?