Hidden+Messages-Justin

Hidden messages.

By: Justin Hofmann Materials · Paper · Cotton balls · Ammonia-water solution (household ammonia from the grocery store) · [|Safety glasses] · __Spray botttles__ Phenolphthalein Experiment: 1. Place a piece of paper on the table. 2. Using a cottem ball, write the hidden message using the Phenolphthalein  then let it dry. 3. Once dry spray the paper with the ammonia to reveal the hidden message.

Similar Experiment Golden Rod Paper [] Practical uses : -Indicators are used to determine pool water quality so it doesn’t damage the skin. -Farmers use indicators to determine soil quality. -Use in production of Shampoo to make sure it doesn’t damage your scalp. -Litmus in an Acid-Base indicator that turns red when acidic and blue when basic.

Explanation : In the hidden messages experiment we see how a base can change the color of certain substances in this case the Phenolphthalein. The ammonia in this experiment is the base. When ammonia is added to the paper containing Phenolphthalein,  the color where the message is hidden shows up purple in color. This is because the pH of the paper is not neutral anymore. Instead it has a pH higher than 7. After the paper sits for a few minutes, the red color seems to disappear. This is due to the carbon dioxide in the air which is slightly acidic. When the acidic carbon dioxide reacts with the basic ammonium, they combine to make the pH neutral which changes the color back to its normal state. If you were to use an acid in this experiment, the phenolphthalein will change to orange.

We have learned about this in chemistry this year and last year. When we learned it, we found out that substances are used to determine if another substance is acidic or basic. One in specific was the use of litmus which either changes red or blue. When the litmus turns red the substance is said to be acidic and when it turns blue it is basic. A pH less than 7 is acidic and a pH higher than 7 is basic. This seems different from the experiment but this is because the goldenrod paper is a different type of indicator than the litmus. We use bases and acids a lot in class to do labs in the back of the room. In one we used an acid to break down a substance to show a single replacement reaction. One last indicator that I found was red cabbage water which changes a variety of colors depending on the pH. Photos :

Sources :  "Hidden Messages - Goldenrod Paper at Steve Spangler Science." //Science Projects Experiments, Educational Toys & Science Toys//. Web. 17 Feb. 2010. ."Phenolphthalein -." //Wikipedia, the free encyclopedia//. Web. 18 Feb. 2010. .