Lab10-S08-Secret_Writing - Lab 10 Secret Writing Laboratory...

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Laboratory Goals In this lab you will: Apply logic and deductive reasoning to try to determine the chemical procedure used in a secret writing process. Use your chemical knowledge to understand why the method of secret writing is chemically effective. Attempt to decipher the secret location for your lab. Safety Notes You will be working with 30% hydrogen peroxide. This chemical will burn any skin it comes in contact with. You should wear goggles at all times and gloves are recommended when using hydrogen peroxide. Introduction Secret writing is as old as writing itself and can be traced back to the Egyptians and other civilizations that needed to communicate. For thousands of years, governments have sought to keep and acquire secrets from rival nations. To prevent state secrets and military plans from falling into the wrong hands they developed codes and ciphers to disguise messages so that only the recipient could read it. What started as code-making and breaking departments evolved into the huge intelligence bureaucracies we know today. Terrorists or spies who work in industry also use secret writing to communicate covertly. Secret Writing is a spy’s classic method of communicating. For this week’s lab you will be donning the mantle of counter-intelligence officers and try to decipher an intercepted message. Secret Writing There are two forms of secret writing and they both share the goal of disguising writing and then making it readable. Cryptography is an encryption method and involves representing words, letters or numbers in some other form. While codes change whole words or phrases into another word, number, or symbol, ciphers replace letters rather than whole words. These messages are visible but encrypted before the message is sent using a key like you see in a kids secret decoder ring. The second form of secret writing is to send an “invisible” message that needs to be made visible. Most of these methods are chemically based and therefore the invisible writing needs a developer to be seen. Invisible ink will be the focus of this lab. This method typically involves writing out a message with a stable chemical invisible to the naked eye. To read the message, the reader applies a specific set of developing chemicals – a reagent -- to make the message appear like a photograph in a darkroom tray. Heat is the most common method used to reveal the writing. An example of this is highlighted in Chapter 3 problem 114 of your textbook (and you can use the CD that comes with your book too!) Lemon juice is the most popular home grown method used to disguise writing. 10-1
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This note was uploaded on 04/15/2009 for the course LB 171L taught by Professor All during the Spring '08 term at Michigan State University.

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Lab10-S08-Secret_Writing - Lab 10 Secret Writing Laboratory...

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