How to Prepare 6M Phosphoric Acid
Preparing 6M phosphoric acid is a common task in chemical laboratories, especially when conducting experiments that require the use of this strong acid. Phosphoric acid, with its chemical formula H3PO4, is a triprotic acid that plays a crucial role in various industrial processes, including food processing, metal finishing, and pharmaceutical manufacturing. In this article, we will discuss the steps and safety precautions involved in preparing 6M phosphoric acid solutions.
Materials and Equipment
Before starting the preparation process, gather the following materials and equipment:
– Pure phosphoric acid (98-99% purity)
– Distilled water
– Measuring cylinder or graduated cylinder
– Beaker
– Safety goggles
– Lab coat
– Gloves
– Stirring rod
– pH meter (optional)
Step 1: Safety Precautions
Always prioritize safety when working with concentrated acids. Before starting, ensure you are wearing safety goggles, a lab coat, and gloves. Phosphoric acid is corrosive and can cause severe burns to the skin and eyes. In case of contact with skin or eyes, rinse immediately with plenty of water and seek medical attention if necessary.
Step 2: Measure the Phosphoric Acid
Using a measuring cylinder or graduated cylinder, carefully measure the required amount of pure phosphoric acid. The concentration of the phosphoric acid should be 98-99% purity. For a 6M solution, you will need approximately 186.4 grams of phosphoric acid for every liter of solution.
Step 3: Dilute the Phosphoric Acid
Pour the measured phosphoric acid into a beaker. Then, slowly add distilled water to the beaker while stirring continuously. It is crucial to add the acid to the water, not the other way around, as the reaction between the two can release a significant amount of heat. Continue stirring until the phosphoric acid is completely dissolved.
Step 4: Adjust the Concentration
After dissolving the phosphoric acid, you may need to adjust the concentration to achieve the desired 6M solution. To do this, measure the pH of the solution using a pH meter. If the pH is too low, add more phosphoric acid in small increments and retest the pH. If the pH is too high, add distilled water in small increments and retest the pH.
Step 5: Final Check
Once the desired concentration is achieved, perform a final check by measuring the pH again. Ensure that the solution is within the desired range before using it in your experiments.
Conclusion
Preparing 6M phosphoric acid requires careful attention to safety and precise measurements. By following these steps and using the appropriate equipment, you can successfully prepare a 6M phosphoric acid solution for your laboratory needs. Always prioritize safety and take necessary precautions to avoid accidents when working with concentrated acids.
