How Disappearing INK works Experiment

Objective: To discover how disappearing ink works.

Materials:
* Bottle of disappearing ink – available at magic or novelty stores Link
* Clear plastic cup
* Seltzer water – or other acidic liquid such as vinegar or lemon juice
* Ammonia

Safety Precautions: Disappearing ink is toxic if ingested. Ammonia is also tonic if ingested. Do not inhale ammonia fumes. Do in a well ventilated area.

Procedure:
Squirt some disappearing ink on a white shirt. It will turn clear in a short time.
Add a little disappearing ink to a clear cup. Next, add a little Seltzer water to the cup. Observe the color change.Objective: To discover how disappearing ink works.

Materials:
* Bottle of disappearing ink – available at magic or novelty stores Link
* Clear plastic cup
* Seltzer water – or other acidic liquid such as vinegar or lemon juice
* Ammonia

Safety Precautions: Disappearing ink is toxic if ingested. Ammonia is also tonic if ingested. Do not inhale ammonia fumes. Do in a well ventilated area.

Procedure:
Squirt some disappearing ink on a white shirt. It will turn clear in a short time.
Add a little disappearing ink to a clear cup. Next, add a little Seltzer water to the cup. Observe the color change.
Add a little ammonia to the same cup. Observe the color change.

Explanation:
Disappearing ink is mostly water, with a little thymolphthalein indicator added. A small amount of basic substance is also added, which causes the thymolphthalein to turn a deep purple color. Thymolphthalein is a base indicator, which turns purple in a base and clear in a acid. More specifically, it begins to turn purple at pH of around 9 or greater, but is clear if the pH is lower than this.

Disappearing ink becomes invisible on your clothes, because CO2 from the air reacts with the water in the solution to form carbonic acid. This lowers the pH, turning the thymolphthlein colorless.

When the seltzer water was added, the thymolphthalein turned clear, because seltzer water contains carbonic acid. When ammonia was added, the carbonic acid was neutralized. This caused the thymolphthalein to turn purple since ammonia is a base.
Add a little ammonia to the same cup. Observe the color change.

Explanation:
Disappearing ink is mostly water, with a little thymolphthalein indicator added. A small amount of basic substance is also added, which causes the thymolphthalein to turn a deep purple color. Thymolphthalein is a base indicator, which turns purple in a base and clear in a acid. More specifically, it begins to turn purple at pH of around 9 or greater, but is clear if the pH is lower than this.

Disappearing ink becomes invisible on your clothes, because CO2 from the air reacts with the water in the solution to form carbonic acid. This lowers the pH, turning the thymolphthalein colorless.

When the seltzer water was added, the thymolphthalein turned clear, because seltzer water contains carbonic acid. When ammonia was added, the carbonic acid was neutralized. This caused the thymolphthalein to turn purple since ammonia is a base.