Understanding Titration Calculations
Titration is a quantitative chemical analysis method used to determine the concentration of an identified analyte (the unknown solution). It involves slowly adding a solution of known concentration (the titrant or standard solution) to a solution of unknown concentration (the analyte) until the reaction reaches its equivalence point. The equivalence point is the point at which the moles of titrant added are stoichiometrically equal to the moles of analyte present.
The Principle of Titration
The core principle behind titration calculations relies on stoichiometry – the quantitative relationship between reactants and products in a chemical reaction. At the equivalence point, the number of moles of the known reactant (from the standard solution) precisely reacts with the number of moles of the unknown reactant (from the analyte solution) according to their stoichiometric ratio in the balanced chemical equation.
The general formula used for titration calculations is derived from the mole concept:
(Molarity_known × Volume_known) / Stoichiometric_coeff_known = (Molarity_unknown × Volume_unknown) / Stoichiometric_coeff_unknown
Where:
- Molarity (M) is the concentration in moles per liter (mol/L).
- Volume (V) is the volume of the solution, typically in liters (L) or milliliters (mL). It's crucial that the units for both volumes are consistent (e.g., both in mL or both in L).
- Stoichiometric Coefficient (n) is the coefficient of the substance in the balanced chemical equation.
This formula can be rearranged to solve for the unknown molarity:
Molarity_unknown = (Molarity_known × Volume_known × Stoichiometric_coeff_unknown) / (Volume_unknown × Stoichiometric_coeff_known)
How to Use the Titration Calculator
Our Titration Calculator simplifies the process of determining the molarity of an unknown solution. Simply input the known values from your titration experiment, and the calculator will provide the molarity of your analyte.
Example Titration Calculation:
Suppose you are titrating 20.0 mL of an unknown hydrochloric acid (HCl) solution with a 0.100 M sodium hydroxide (NaOH) solution. You find that it takes 25.0 mL of the NaOH solution to reach the equivalence point. The balanced chemical equation for this reaction is:
HCl (aq) + NaOH (aq) → NaCl (aq) + H₂O (l)
From the balanced equation, the stoichiometric coefficients for both HCl and NaOH are 1.
- Molarity of Known Solution (NaOH): 0.100 M
- Volume of Known Solution Used (NaOH): 25.0 mL
- Volume of Unknown Solution Titrated (HCl): 20.0 mL
- Stoichiometric Coefficient of Known Solution (NaOH): 1
- Stoichiometric Coefficient of Unknown Solution (HCl): 1
Using the formula:
Molarity_unknown (HCl) = (0.100 M × 25.0 mL × 1) / (20.0 mL × 1)
Molarity_unknown (HCl) = 2.5 / 20.0 = 0.125 M
Therefore, the molarity of the unknown HCl solution is 0.125 M.
Titration Molarity Calculator
Enter the values below to calculate the molarity of your unknown solution.