0.1 Phosphoric Acid Preparation
Phosphoric acid is a strong acid commonly used in various industries such as food, cosmetic, and pharmaceutical. In laboratory settings, phosphoric acid is often used as a reagent for various chemical reactions and as a buffer solution. Preparing phosphoric acid of a specific concentration, such as 0.1 M, is crucial for precise and accurate results.
Materials Needed
- 85% Phosphoric acid (H3PO4)
- Distilled water
- Analytical balance
- Volumetric flask (100 mL)
Preparation of 0.1 M Phosphoric Acid
Step 1: Calculate the Amount of Phosphoric Acid Needed
To prepare 100 mL of 0.1 M phosphoric acid, calculate the amount of phosphoric acid needed using the following formula:
Molarity (M) = moles of solute / liters of solution
Rearrange the formula to solve for moles of solute:
moles of solute = Molarity (M) x liters of solution
moles of solute = 0.1 M x 0.1 L = 0.01 moles
The molar mass of phosphoric acid (H3PO4) is 97.97 g/mol. Calculate the mass of phosphoric acid needed:
mass of phosphoric acid = moles of solute x molar mass mass of phosphoric acid = 0.01 moles x 97.97 g/mol = 0.9797 g
Step 2: Weigh the Phosphoric Acid
Using an analytical balance, accurately weigh out 0.9797 g of 85% phosphoric acid.
Step 3: Dissolve the Phosphoric Acid in Distilled Water
Transfer the weighed phosphoric acid to a 100 mL volumetric flask. Gradually add distilled water to the flask while stirring until the acid is completely dissolved.
Step 4: Dilute the Solution to the Mark
Add more distilled water to the flask until the solution reaches the 100 mL mark.
Verifying the Concentration
To verify the concentration of the prepared phosphoric acid solution, perform a titration with a strong base such as sodium hydroxide (NaOH). Alternatively, use a pH meter to measure the pH of the solution and calculate the concentration using the pH value.
Precautions
- Handle phosphoric acid with care, as it is a corrosive substance that can cause skin and eye irritation.
- Wear protective gear, including gloves, goggles, and a laboratory coat, when handling phosphoric acid.
- Prepare the solution in a well-ventilated area to prevent inhalation of acidic fumes.
By following these steps, you can prepare a 0.1 M phosphoric acid solution with high accuracy and precision.
