A 25.00-mL sample of an unknown H₃PO₄ solution is titrated with a 0.150 M NaOH solution. The equivalence point is reached when 22.97 mL of NaOH solution is added. What is the concentration of the unknown H₃PO₄ solution? The neutralization reaction is H₃PO₄(aq) + 3 NaOH(aq) → 3 H₂O(l) + Na₃PO₄(aq)

Verified step by step guidance

1. Determine the moles of NaOH used in the titration. Use the formula: moles = molarity (M) imes volume (L). Convert the volume of NaOH from mL to L before using it in the calculation.
2. Identify the stoichiometry of the reaction between H₃PO₄ and NaOH from the balanced chemical equation. Note that it takes 3 moles of NaOH to neutralize 1 mole of H₃PO₄.
3. Calculate the moles of H₃PO₄ that were neutralized based on the stoichiometry. Divide the moles of NaOH by 3 to find the moles of H₃PO₄.
4. Calculate the molarity of the H₃PO₄ solution. Use the formula: molarity = moles of solute / volume of solution (L). Convert the volume of the H₃PO₄ solution from mL to L before using it in the calculation.
5. The result from the previous step gives the concentration of the H₃PO₄ solution in moles per liter (M).

Key Concepts

Titration

Titration is a quantitative analytical technique used to determine the concentration of a solute in a solution. It involves the gradual addition of a titrant (a solution of known concentration) to a sample until the reaction reaches its equivalence point, where the amount of titrant added is stoichiometrically equivalent to the amount of solute in the sample.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It allows chemists to determine the relationships between the quantities of substances involved in a reaction, such as how many moles of one reactant are needed to completely react with a given amount of another reactant.

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is expressed in units of moles per liter (M) and is crucial for calculations in titration, as it allows for the determination of the amount of solute present in a given volume of solution, facilitating the calculation of unknown concentrations.