How to Prepare 0.1 Phosphoric Acid in Water
Preparing a 0.1 molar phosphoric acid solution in water is a common task in chemistry laboratories. Phosphoric acid is a versatile chemical used in various industries, including food, pharmaceuticals, and agriculture. It is essential to follow proper procedures to ensure the accuracy and safety of the solution. In this article, we will guide you through the steps to prepare a 0.1 molar phosphoric acid solution in water.
Materials Needed
Before starting the preparation, gather the following materials:
– Phosphoric acid (H3PO4) pellets or concentrated phosphoric acid solution
– Distilled water
– A clean, dry beaker
– A magnetic stirrer or stirring rod
– A balance or scale
– A volumetric flask (100 mL or 250 mL, depending on the desired concentration)
– Safety equipment, such as gloves, goggles, and a lab coat
Step 1: Calculate the Required Amount of Phosphoric Acid
First, determine the amount of phosphoric acid needed to prepare a 0.1 molar solution. The molarity (M) is defined as the number of moles of solute (phosphoric acid) per liter of solution. The molar mass of phosphoric acid is approximately 98.00 g/mol.
To calculate the required amount of phosphoric acid, use the following formula:
Moles of H3PO4 = Molarity × Volume (in liters)
For a 0.1 molar solution, you will need:
Moles of H3PO4 = 0.1 M × 1 L = 0.1 moles
Now, convert moles to grams using the molar mass:
Grams of H3PO4 = Moles of H3PO4 × Molar mass
Grams of H3PO4 = 0.1 moles × 98.00 g/mol = 9.8 g
Therefore, you will need 9.8 grams of phosphoric acid to prepare a 0.1 molar solution.
Step 2: Weigh the Phosphoric Acid
Using a balance or scale, weigh out 9.8 grams of phosphoric acid pellets. Be sure to handle the pellets with gloves to avoid any skin contact.
Step 3: Dissolve the Phosphoric Acid in Water
Pour 50 mL of distilled water into a clean, dry beaker. Gradually add the weighed phosphoric acid pellets to the beaker while stirring continuously. The reaction may release heat, so be cautious while adding the pellets.
Once the phosphoric acid is completely dissolved, transfer the solution to a volumetric flask using a funnel. Rinse the beaker with distilled water and add the rinse water to the volumetric flask to ensure all the phosphoric acid is transferred.
Step 4: Adjust the Volume to the Mark
Add distilled water to the volumetric flask until the solution reaches the 100 mL or 250 mL mark, depending on the desired concentration. Use a dropper or pipette to make precise adjustments.
Step 5: Stir and Allow to Cool
Stir the solution thoroughly to ensure complete mixing. If the solution becomes too hot during the preparation, allow it to cool down before proceeding.
Step 6: Final Checks
Once the solution has cooled, check the molarity using a pH meter or a titration method. Adjust the concentration if necessary by adding more phosphoric acid or water.
Congratulations! You have successfully prepared a 0.1 molar phosphoric acid solution in water. Always handle phosphoric acid with care and follow proper safety procedures to prevent accidents.
