New Recording 4

Experiment Overview

• Objective: To observe color changes in red cabbage indicator as pH changes.

Materials Used

• Red Cabbage: 5 grams

• Water: 50 milliliters

• HCl (Hydrochloric Acid): 6 molar concentration

• NaOH (Sodium Hydroxide): 1 molar, diluted to 0.1 molar for titration

• Hot Plate: Set to 190 degrees Celsius

Procedure

• Preparation of Red Cabbage Indicator

  • Weighed out 5 grams of red cabbage and added it to 50 milliliters of water.

  • Heated the mixture on a hot plate at 190 degrees Celsius for 10-15 minutes until the water turned purple due to pigment extraction.

• Acidification

  • Acidified the solution to a pH of about 2.3 by adding 3 drops of 6 M HCl.

• Initial Titration Attempt

  • Attempted to titrate using 1 M NaOH, which caused a rapid pH increase from 2.3 to approximately 11 within half a milliliter.

• Dilution for Titration

  • Created a 0.1 M NaOH solution by mixing 5 milliliters of 1 M NaOH with 50 milliliters of water.

  • Filled the burette with this 0.1 M NaOH for titration.

Observations During Titration

• Color Changes Noted:

  • As NaOH was added, the color transitioned through several stages:

    • Pink (acidic)

    • Purple (neutral)

    • Teal

    • Green

    • Yellow (alkaline)

  • The most significant color change, from purple to teal, occurred around pH 7.

  • Not all data points were recorded accurately due to drop counter errors.

• pH Stability

  • After reaching pH 10, subsequent additions of NaOH had little effect on pH, which peaked at about 12.25 with the full 50 milliliters of 0.1 M NaOH.