If 250 ml of NaOH solution neutralizes 0.5 L of 3.0*10^-1 M H3PO4, what is the molarity of NaOH solution?

Answer 1

You need to write the balanced equation:

3NaOH + H₃PO₄ ==> Na₃PO₄ + 3H₂O

Note that it takes 3 moles NaOH for every 1 moles H₃PO₄

moles H₃PO₄ = 0.5 L x 3.0x10^-1 mol/L = 1.5x10^-1 moles = 0.15 moles H₃PO₄

moles NaOH needed = 3 x 0.15 = 0.45 moles NaOH required

molarity of NaOH = moles/liter = 0.45 moles/0.250 L = 1.8 M NaOH