To prepare a 0.1% phenolphthalein indicator solution using 70% ethanol, follow these steps:
1. Determine the volume of the final solution needed. Let's assume you want to prepare 100 mL of the solution.
2. Calculate the amount of phenolphthalein needed. For a 0.1% solution, you'll need 0.1 grams of phenolphthalein for every 100 mL of solution.
3. Measure out the required amount of phenolphthalein powder using a balance. For example, for 100 mL, you'll need 0.1 grams of phenolphthalein.
4. Transfer the measured phenolphthalein powder into a clean, dry glass container.
5. Add 70 mL of 70% ethanol to the container. This leaves 30 mL remaining to reach the final volume of 100 mL.
6. Stir or shake the solution thoroughly until the phenolphthalein powder is completely dissolved in the ethanol.
7. Once dissolved, add more 70% ethanol to the container to bring the total volume up to 100 mL.
8. Mix the solution well to ensure uniformity.
Your 0.1% phenolphthalein indicator solution in 70% ethanol is now ready for use. Store it in a tightly sealed container away from light to prevent degradation.
