Results: Each of the pigments has a distinct alkaline and acid colour and can therefore be used as a pH indicator. Vanilla is an olfactory (ie smell) indicator. You can’t smell the vanilla in a basic solution because the vanillin molecule ionizes although you can smell it in a neutral or acidic solution Caution: HCl and NaOH are corrosive, avoid contact with skin. In case of contact with skin wash with plenty of water. Ethanol is volatile and flammable, perform in a well ventilated area with no open flames. Clean up: All solutions can be flushed down the sink. 4. Secret Writing Equipment: Cotton buds/ matchsticks Sheets of paper Plastic bottle One spray bottle One or two plastic cups Sponge Black light light-box Reagents: Phenolpthalein indicator Laundry detergent Starch solution or rinse water from rice or potatoes or cornflour solution; 1 teaspoon of cornflour) Tonic Water I2 (about 1 nickel spoon full), or tincture of iodine (1 mL) Water Preparation: Put the vitex or starch solution into a plastic bottle. If using corn flour, mix a teaspoon of corn flour with ¼ cup of cold water in plastic cup. Cook in a microwave for 1 minute, stirring after 15 seconds and at the end. Cool. Dissolve some laundry powder in water in the spray bottle. Dissolve the I2 in 10-15 mL of water and put in the plastic cup. Procedure: Use a cotton bud to write on the paper with the phenolphthalein, starch solution and tonic water. Let the paper dry. the writing, spraying with the laundry powder solution “Develop” for the phenolphthalein to show pink writing and sponging over the I2 solution for the starch show blue writing. The quinine in tonic water fluoresces and can be seen using the black light box.
Results: Each of the pigments has a distinct alkaline and acid colour and can therefore be used as a pH indicator. Vanilla is an olfactory (ie smell) indicator. You can’t smell the vanilla in a basic solution because the vanillin molecule ionizes although you can smell it in a neutral or acidic solution Caution: HCl and NaOH are corrosive, avoid contact with skin. In case of contact with skin wash with plenty of water. Ethanol is volatile and flammable, perform in a well ventilated area with no open flames. Clean up: All solutions can be flushed down the sink. 4. Secret Writing Equipment: Cotton buds/ matchsticks Sheets of paper Plastic bottle One spray bottle One or two plastic cups Sponge Black light light-box Reagents: Phenolpthalein indicator Laundry detergent Starch solution or rinse water from rice or potatoes or cornflour solution; 1 teaspoon of cornflour) Tonic Water I2 (about 1 nickel spoon full), or tincture of iodine (1 mL) Water Preparation: Put the vitex or starch solution into a plastic bottle. If using corn flour, mix a teaspoon of corn flour with ¼ cup of cold water in plastic cup. Cook in a microwave for 1 minute, stirring after 15 seconds and at the end. Cool. Dissolve some laundry powder in water in the spray bottle. Dissolve the I2 in 10-15 mL of water and put in the plastic cup. Procedure: Use a cotton bud to write on the paper with the phenolphthalein, starch solution and tonic water. Let the paper dry. “Develop” the writing, spraying with the laundry powder solution for the phenolphthalein to show pink writing and sponging over the I2 solution for the starch show blue writing. The quinine in tonic water fluoresces and can be seen using the black light box.
demonstrations.docx