Potassium hydrogen phthalate is a solid, monoprotic acid frequently used in the laboratory to standardize strong base solutions. It has the unwieldy formula of KHC8H4O4. This is often written in shorthand notation as KHP. Of 5.06 grams of KHP are needed to exactly neutralize 35.3 mL of a barium hydroxide solution, what is the concentration of the base solution

Question: Potassium hydrogen phthalate is a solid, monoprotic acid frequently used in the laboratory to standardize strong base solutions. It has the unwieldy formula of KHC8H4O4. This is often written in shorthand notation as KHP. Of 5.06 grams of KHP are needed to exactly neutralize 35.3 mL of a barium hydroxide solution, what is the concentration of the base solution?

Explanation and

2KHP + Ba(OH)2 ---> 2H2O + Ba(KP)2

you need 2 moles of KHP to neutralise 1 mole of Ba(OH)2

moles KHO = mass / molar mass  

= 2.43 g / 204.22 g/mol  

= 0.0118989 mol

moles Ba(OH)2 = 1/2 x moles KHP

= 0.005949 mol

Molarity Ba(OH)2 = moles / Litres

= 0.005949 mol / 0.0213 L

= 0.279 M (3 sig figs)