How to Calculate the Molarity of Phosphoric Acid Solution?

Question:

What is the molarity of a solution of phosphoric acid if 0.511g of potassium bicarbonate was used to neutralize 35.4-mL of the phosphoric acid solution?

Answer:

To find the molarity of the phosphoric acid solution, we need to use the balanced equation between phosphoric acid and potassium bicarbonate.

Explanation:

To find the molarity of the phosphoric acid solution, we need to use the balanced equation between phosphoric acid and potassium bicarbonate:

H3PO4 + KHCO3 -> K2HPO4 + CO2 + H2O

From the equation, we can see that one mole of phosphoric acid reacts with one mole of potassium bicarbonate. Therefore, we can calculate the number of moles of phosphoric acid by dividing the mass of potassium bicarbonate by its molar mass (using the periodic table) and then converting this to moles of phosphoric acid using the stoichiometry of the equation.

Next, we calculate the molarity of the phosphoric acid solution by dividing the moles of phosphoric acid by the volume of the solution in liters.

So the molarity of the phosphoric acid solution is the moles of phosphoric acid divided by the volume of the solution in liters.