Types of Titrations

1. Acid-Base Titrations:

   • Involve the neutralization reaction between an acid and a base.

   • Example: Determining the concentration of HClHClHCl using NaOHNaOHNaOH as the titrant.

2. Redox Titrations:

   • Based on oxidation-reduction reactions.

   • Example: Determining the concentration of Fe2+Fe^{2+}Fe2+ using KMnO4KMnO_4KMnO4​.

3. Complexometric Titrations:

   • Involve the formation of a complex ion.

   • Example: Determining metal ions using EDTAEDTAEDTA.

4. Precipitation Titrations:

   • Based on a reaction that forms a precipitate.

   • Example: Determining Cl−Cl^-Cl− concentration using AgNO3AgNO_3AgNO3​.

Equipment and Setup

• Burette: Contains the titrant and delivers it in precise amounts.

• Pipette: Used to measure a specific volume of the analyte.

• Erlenmeyer Flask: Holds the analyte.

• Indicator: A chemical that changes color at the equivalence point in acid-base titrations (e.g., phenolphthalein or methyl orange).

Steps in a Titration

1. Preparation:

   • Rinse the burette with the titrant and fill it.

   • Rinse the pipette with the analyte and measure its volume into the flask.

   • Add a few drops of indicator to the analyte.

2. Titration:

   • Slowly add the titrant to the analyte while swirling the flask.

   • Stop adding titrant when the indicator changes color (end point).

3. Data Collection:

   • Record the initial and final burette readings to calculate the volume of titrant used.

4. Calculation:

   • Use the titration equation to find the unknown concentration.

Acid-Base Titrations

Neutralization Reaction

• General Reaction: Acid + Base → Salt + Water

• Example: HCl+NaOH→NaCl+H2O

Key Terms:

1. Equivalence Point:

   • The point at which the moles of acid equal the moles of base.

   • For strong acid-strong base titrations, this is pH=7\text{pH} = 7pH=7.

2. End Point:

   • The point where the indicator changes color, close to the equivalence point.

3. Indicators:

   • Choose an indicator that changes color at the pH of the equivalence point.

   • Examples:

     • Phenolphthalein: Colorless in acid, pink in base (pH range 8.2–10).

     • Methyl orange: Red in acid, yellow in base (pH range 3.1–4.4).

Titration Curve

A titration curve plots the pH of the solution against the volume of titrant added.

1. Strong Acid-Strong Base:

   • Starts at a low pH (acidic).

   • Sharp increase at the equivalence point (pH=7).

   • Levels off at a high pH (basic).

2. Weak Acid-Strong Base:

   • Starts at a slightly higher pH.

   • Equivalence point above pH=7\text{pH} = 7pH=7 due to the formation of a weak conjugate base.

3. Weak Base-Strong Acid:

   • Starts at a slightly lower pH.

   • Equivalence point below pH=7\text{pH} = 7pH=7 due to the formation of a weak conjugate acid.

Titration Calculations

Key Formula: $M_1V_1 = M_2V_2$

Where:

• M1M_1M1​: Molarity of the titrant.

• V1V_1V1​: Volume of the titrant.

• M2M_2M2​: Molarity of the analyte.

• V2V_2V2​: Volume of the analyte.