Question

What amount of water is formed when 20 mL of 0.80 M HCl and 30 mL of 0.40 M NaOH are mixed?

Answer 1

The balanced equation is

NaOH + HCl -----> NaCl + H2O

Number of moles of NaOH = molarity * volume of solution in L

Number of moles of NaOH = 0.40 * 0.030 L = 0.012 mole

Number of moles of HCl = 0.80 * 0.02 L = 0.016 mole

From the balanced equation we can say that

1 mole of NaOH requires 1 mole of HCl so

0.012 mole of NaOH will require

= 0.012 mole of NaOH *( 1 mole of HCl / 1 mole of NaOH)

= 0.012 mole of HCl

But we have 0.016 mole of HCl which is in excess so NaOH is limiting reactant

From the balanced equation we can say that

1 mole of NaOH produces 1 mole of H2O so

0.012 mole of NaOH will produce 0.012 mole of H2O

mass of 1 mole of H2O = 18.015 g so

the mass of 0.012 mole of H2O = 0.216 g

Therefore, the mass of H2O produced would be 0.216 g