Question

1) What will be the coefficient for NaOH when this equation is balanced? (There will be complete neutralization of the triprotic acid.)

H₃PO₄ (aq) +   NaOH (aq)  →    Na₃PO₄ (aq) + H₂O (l)

2) If we used 20.0 mL of a 0.10 M solution of NaOH, how many moles of NaOH did we use?

Answer 1

1)The balanced equation is

H₃PO₄ (aq) + 3 NaOH (aq)  →    Na₃PO₄ (aq) + 3 H₂O (l)

Explanation: In order to balance an equation we must ensure that the number of atoms of each species on right side of the equation must be equal to the number of atoms of each species on left side of the equation.

2) Molarity of NaOH = number of moles of NaOH / volume of solution in L

0.10 = number of moles of NaOH / 0.0200 L

number of moles of NaOH = 0.10 * 0.02 = 0.002 mole

Therefore, the number of moles of NaOH used = 0.002 mol