The reaction of sulfuric acid (H2SO4) with potassium hydroxide (KOH) is described by the equation:
H2SO4 + 2KOH → K2SO4 + 2H2O
Suppose 50 mL of KOH with unknown concentration is placed in a flask with bromthymol blue indicator. A solution of 0.10 M H2SO4 is dripped into the KOH solution. After exactly 33.4 mL of H2SO4 is added, the indicator changes from blue to yellow. What is the concentration of the KOH?
Explanation: Because 1 mole of sulfuric acid reacts with 2 moles of potassium hydroxide, there are twice as many moles of KOH at the equivalence point as moles of H2SO4.
