Answer:
unknown concentration of CH₃COOH = 0.2128 mol/L
Volumetric Analysis: Titration
Volumetric analysis is a quantitative laboratory technique used to determine the concentration of a solution by reacting it with a standard solution. A simple titration is an example of volumetric analysis, with others being back titrations, and double titrations
A Simple titration involves the slow adding of one solution of a unknown concentration (known as titrant), from a burette, to another solution, in a conical flask, of known volume and known concentration (known as a standard solution) The titrant is added until the second solution is neutralised by the titrant, which is often apparent via colour change from using an indicator. This point where the colour change occurs, is called the end point, and marks when the reaction is complete.
The volume of titrant used to neutralise the standard solution, is known as the titre, and is used in volumetric analysis, to calculate the unknown concentration of the titrant.
In titration of 0.02500 L of 0.166 mol/L NaOH (standard solution = flask), with a CH₃COOH titrant (unknown concentration = burette), the titre required to meet end point = 0.0195 L of CH₃COOH
To find the concentration, we require moles, and volume (titre). To calculate moles, we can consider the equation of the reaction:
CH₃COOH(aq) + NaOH(aq) → NaCH₃COO(aq) + H₂O(l)
The stoichiometry of the above reaction is 1 : 1. Therefore:
moles of CH₃COOH = moles of NaOH
Stoichiometry:
The ratio of coefficients of reactants and products in a reaction equation, is known as the stoichiometry of the reaction.
Thus, mol(NaOH) = concentration×Volume
= 0.166×0.02500 = 4.15×10⁻³ mol
mol(NaOH) = mol(CH₃COOH) = 4.15×10⁻³ mol
Therefore, concentration of CH₃COOH = mol/volume (titre)
= 4.15×10⁻³/0.0195 = 0.2128 mol/L
∴ unknown concentration of CH₃COOH = 0.2128 mol/L