Titration experiment

Acid-Base Titration Experiment

(Determining the concentration of an unknown acid solution)

Objective:

To analyze the concentration of a hydrochloric acid (HCl) solution by titrating it with a sodium hydroxide (NaOH) solution of known concentration.

Materials:

• 0.1 M sodium hydroxide (NaOH) solution
• Hydrochloric acid (HCl) solution (unknown concentration)
• Phenolphthalein indicator (to detect the endpoint)
• Burette
• Conical flask
• Pipette
• Beaker
• White paper (for visibility of color change)
• Distilled water
• Safety goggles and gloves

Procedure:

1. Preparation of Solutions:
   • Fill the burette with the NaOH solution. Make sure it’s clean and filled without any air bubbles.
   • Use the pipette to transfer a known volume (e.g., 25 mL) of the HCl solution into the conical flask.
2. Add Indicator:
   • Add 2-3 drops of phenolphthalein to the HCl solution. The solution will remain colorless at the beginning.
3. Titration:
   • Slowly add the NaOH solution from the burette into the conical flask, constantly swirling the flask.
   • As the titration proceeds, the HCl reacts with the NaOH, neutralizing the acid.
   • When the solution in the conical flask changes from colorless to a faint pink, the reaction has reached its endpoint. This color change indicates that the acid has been completely neutralized.
4. Record the Volume of NaOH Used:
   • Note the volume of NaOH used from the burette when the endpoint is reached.
5. Repeat the Titration:
   • Perform at least 2 more titrations for accuracy and calculate the average volume of NaOH used.

Calculation:

Now that you know the volume of NaOH used, you can calculate the concentration of HCl using the following formula: C1​×V1​=C2​×V2​ Where:

• C1​ = concentration of NaOH
• V1​ = volume of NaOH used (in liters)
• C2​ = concentration of HCl (unknown, the value you're solving for)
• V2​ = volume of HCl solution used (in liters)

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Biochemical Concept:

• Analytical chemistry involves measuring the quantities of chemical substances.
• Titration is a technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration.
• Indicators (like phenolphthalein) help detect the endpoint of the reaction, signaling when the reaction has reached completion.

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This experiment provides an introduction to quantitative analysis in chemistry, demonstrating how precise measurements can be made to calculate unknown concentrations—essential in many areas of analytical chemistry!