Question

Weak acid-base indicator equilibria

Step 1: Obtain a small test tube and add approximately 5mL water. Next, add 10 drops of a methyl violet indicator, and record the color of the solution.

            Step 2: Add ~4 drops of 6 M HCl to the solution, and record the color of the solution.

            (be careful when handling concentrated acids and bases)

            Step 3: Add 6 M NaOH until the color of the solution shifts back to its original color.     Estimate the pH range of the solution. You may also test the acidity with a pH paper.

            Step 4: Add a small test tube, and add approximately 5 mL water. Next add 10 drops of cabbage juice, and record the color of the solution.

            Step 5: Add ~4 drops of 6 M NaOH to the solution and record the color of the solution.

            Step 6: Add 6 M HCl until the color of the solution shifts back to its original color. Estimate the pH range of the solution from the color of the solution. You may also test the acidity with a pH paper.

Water + Methyl Violet Test Tube 1 Add 6 M HCI Add 6 M NaOH Color of theurPle solution /2 The pH range pH-paper results Water + Cabbage Juice Add 6 M Na0H Add 6 M HCI Test Tube 2 Color of the solution The pH range /2 pH-paper results l0

1.Write the equilibrium reactions.

2. Calculate the concentration of the hydronium ion from the pH value,

Answer 1

Methul violet Punple -12 NaoH он 에白 OR neen cabbaje juice