When you add a pH indicator extracted from red cabbage to a solution and it changes to a blue color, you are observing a shift in color that suggests the nature of the solution based on its pH level. Red cabbage contains a pigment called anthocyanin, which changes color depending on the pH of the solution it is in.
Let's analyze the color changes:
1. Acidic Solutions: These solutions have a high concentration of H+ ions. In the presence of red cabbage juice, acidic solutions typically turn the indicator colors like red or pink.
- Examples: Vinegar, sulfuric acid
2. Neutral Solutions: A neutral solution has a pH of around 7, and red cabbage juice will typically produce a purplish color in neutral conditions.
- Examples: Distilled water
3. Basic Solutions: These solutions have a lower concentration of H+ ions and are higher in OH- ions. Basic solutions will turn red cabbage juice blue or green.
- Example: Baking soda in distilled water
Given the potential color changes:
- A solution with a lot of H+ (i.e., acidic) would not result in a blue color; instead, it would produce a red or pink color.
- Vinegar (acidic) would also turn the indicator red or pink.
- Distilled water is neutral and would result in a purplish color, not blue.
- Sulfuric acid (strongly acidic) would certainly turn the indicator red or pink.
The solution that is basic in nature (causing the indicator to turn blue) is baking soda in distilled water.
Therefore, the most likely solution that caused the red cabbage pH indicator to change to a blue color is:
baking soda in distilled water.
