Aim 1: To identify and prepare a natural indicator using red cabbage.
Aim 2: To use the natural indicator and two other commercial indicators (universal indicator and phenolphthalein) to classify five household substances as acidic, basic or neutral.
An indicator is a substance that, in solution changes colour depending on whether the solution is acidic or basic . Many plants and flowers have natural substances which have indicating properties that allow them to be used as indicators . One of the best natural indicators can be extracted from red cabbage.
The red colour of red cabbage comes from a molecule called an anthocyanin . The red cabbage dye reacts with acids or bases resulting in changes at the molecular level which causes their colour to be different at different pH levels. Anthocyanin is also found in other plants and flowers such as apples, cornflowers and grapes .
The colour of the red cabbage dye changes in response to changes in the concentration of hydrogen (H+) or hydronium (H₃O+) ions . The higher the concentration of hydrogen (H+) and hydronium (H₃O+) ions, the lower the pH of the solution (hence more acidic). Whereas the lower the concentration of hydrogen (H+) and hydronium (H₃O+) ions, the higher the pH of the solution( hence more basic).
Risk Effect Prevention Treatment
Hydrochloric Acid (HCl) - Is a corrosive liquid
- Skin contact: Brief exposure may cause irritation. Prolonged contact may result in burns.
- Eye contact: is irritating and may cause conjunctivitis, ulceration and corneal burns.
Permanent eye damage may result. To avoid any contact with eyes and skin:
- Wear safety glasses
- Wear safety gloves.
- Wear protective clothing
- Wear closed shoes - Eye contact: immediately hold eyelids open and rinse the eye continuously with a gentle stream of clean running water for at least fifteen minutes. Seek urgent medical attention
- Skin Contact: Remove...