More Chemical Reactions

INVISIBLE INK

To make an invisible ink you mix lemon juice with a few drops of water. Then you write on a piece of paper with a cotton bud. Leave the message to dry.

Now you are ready to read the message. Iron over the paper for a while until the message appears. The lemon juice will turn brown.

This happens because there is carbon in the lemon juice. When you heat the lemon juice with an iron the carbon starts to break down and turn brown.

You could send a secret message to your friend.

RUSTY WOOL
How do you quickly turn this steel wool rusty?

Today in science club we found out how. First you need to soak the steel wool in some vinegar. Next you squeeze out the vinegar and place the steel wool in a jar. Now poke a thermometer into the steel wool and put the lid on the jar.

We watched to see what happened to the temperature on the thermometer and notice that it went up from about 17 degrees C to 30 degrees C.
There was also some fog on the inside of the jar.

Last week we found out that if a chemical reaction gives off heat it is called and exothermic reaction. So this must be one.

We also noticed that the steel wool went rusty really quickly.

But what is reacting?

The vinegar removes any protective coating on the steel wool so the steel wool begins to rust. When something rusts it is actually a chemical reaction between the iron and the oxygen in the air. Steel wool is made of iron so it can rust. When rusting occurs heat energy is released.