Question

The precipitation of aluminum hydroxide, Al(OH)_3 (K_sp)=1.3 x10^{-33}), is sometimes used to purify water.

At what pH will precipitation of Al(OH)_3 begin if 5.70 lb ofaluminum sulfate, Al_2(SO_4)_3, is added to 2050 gallons of water(with a negligible change in volume)?

Below are some potentially useful conversion factors.

1 lb = 453.6 g
1 gallon = 4 quarts
1 quart = 0.946 L