Answer :
1.80 x 10^-4 moles/liter OH-
Explanation:
pH = 3.58 ; [H3O+] = 10^-3.58 = 2.63 x 10^-4 moles/liter
pH = 4.08 ; [H3O+] = 10^-4.08 = 8.32 x 10^-5 moles/liter
One needs to remove:
2.63 x 10^-4 moles/liter – 8.32 x 10^-5 = 1.80 x 10^-4 moles H3O+/liter
According to the equation: H3O+ + OH-=⇒ 2H2O
Moles/ liter of OH- needed:
1.80 x 10^-4 moles H3O+/liter x 1 mole OH-/1mole H3O+ = 1.80 x 10^-4 moles/liter OH-