25.00 mL of a H2SO4 solution with an unknown concentration was titrated to a phenolphthalein endpoint with 43.25 mL of a 0.1481 M NaOH solution. What is the concentration of the H2SO4 solution?

Answer 1

First, look at the balanced equation for the titration reaction:

H2SO4 + 2NaOH ==> Na2SO4 + 2H2O ... balanced equation

Next, find the moles of NaOH that were used:

43.25 mls x 1 L / 1000 mls x 0.1481 mol / L = 0.006405 moles NaOH used

Next, equate this to the moles of H2SO4 that are present, using the balanced equation:

0.006405 mols NaOH x 1 mol H2SO4 / 2 mols NaOH = 0.003203 moles H2SO4 present

Finally, using the volume of 25.00 ml H2SO4, calculate the molar concentration:

0.003203 mols H2SO4 / 25.00 ml x 1000 ml / L = 0.1281 mols / L = 0.1281 M