How many milliliters of 4.7 M NaOH solution are needed to neutralize 8.9 mL of 7.8 M H2SO4 solution?

Question

How many milliliters of 4.7 M NaOH solution are needed to neutralize 

8.9 mL

 of 

7.8 M

 

H₂SO₄

 solution?

 

Answer 1

This is an acid-base neutralization reaction. So, first we should write the correctly balanced equation:

2NaOH(aq) + H₂SO4(aq) ==> Na₂SO4(aq) + 2H₂O(l)

Next, we find the moles of H2SO4 that are present:

8.9 ml x 1 L/1000 ml x 7.8 mol/L = 0.06942 moles H2SO4 present

Then, we find how many moles NaOH are needed to neutralize 0.06942 moles H2SO4:

0.06942 mol H2SO4 x 2 mol NaOH/mol H2SO4 = 0.1389 moles NaOH needed

Finally, using the molarity of NaOH, we calculate the volume of NaOH needed:

(x L)(4.7 mol/L) = 0.1389 moles

x =0.1389/4.7 = 0.02955 L x 1000 ml/L = 29.6 ml = 30. mls NaOH (to 2 significant figures)