“Home dry-cleaning” experiment
How to remove ink from the white cotton fiber
An entertaining and simple experiment that you can do with the kids, using “reagents” found in the home.
Reagents and equipment:
- table vinegar (70%);
- potassium permanganate;
- hydrogen peroxide (3%);
- cotton buds;
- cotton fabric;
- ballpoint pen.
Dissolve potassium permanganate in table vinegar. Write some words or draw a picture on cotton fabric. Then apply cotton buds soaked in the permanganate solution to the ink. Wash away the stain with hydrogen peroxide.
Potassium permanganate is a strong oxidizer. It can break down organic compounds with a double or triple bond, for example the dyes in inks. The structure of the inks change, and they become colorless. Additionally, if the manganese solution is left open for a while, it turns brown because of the oxidation of various mixtures contained in the air. Manganese (IV) oxide turns the solution brown, and cannot even be washed away by water. This compound, together with the unreacted potassium permanganate, forms an even worse stain on the T-shirt. The stain can be removed by a 3% solution of hydrogen peroxide. In the reaction with the “stain”, hydrogen peroxide shows its reducing properties. It reduces the unreacted pink potassium permanganate and the brown manganese (IV) oxide to colorless manganese (II) acetate. And the acetic acid helps this reaction to take place, creating a favorable acidic medium.
If 70% acetic acid comes into contact with the eyes or skin, rinse them with copious amounts of cold water, and then with a solution of baking soda.