Question

If i have 1,000,000 gallons of water at a pH of 4.45 how many pounds of NaOH are need to raise this water to a pH of 7.8?

Please show work.

Answer 1

        1,000,000 gallons of water      =    3785411.78 L

at pH = 4.45 ,   [H3O+] = 10^-pH = 10^-4.45 = 3.55*10^-5 M

      at pH = 7.8 , [H3O+] = 10^-pH = 10^-7.8 = 1.585*10^-8 M

the concentration of [H3O+] reduced = (3.55*10^-5)-(1.585*10^-8 ) = 3.548415*10^-5 M

   concentration of [OH-] needed = 3.548415*10^-5 M

    concentration of NaOH needed =   3.548415*10^-5 = W/mwt*1/V

                                                3.548415*10^-5 = (w/40)*(1/3785411.78)

amount of NaOH needed = 5372.9 g

                                                  = 11.845 pound