An element is a chemical made from one type of atom. Oxygen, gold, copper, iron and helium are all elements.
Putting two or more elements together is a compound. Water and acid are compounds. There are lots of different kinds of acid, but all acids change almost everything they touch. Sometimes this change makes a whole new chemical. When this happens it is called a reaction.
Some acids are strong enough to ‘eat’ through rocks and concrete. Other acids can change the color of something they touch or clean dirt off of the things they touch.
Let’s do an experiment to see how acid changes to paper and can turn you into a detective at the same time.
THINGS YOU NEED
- Lemons (3 or 4)
- Cotton swabs
- Plain white paper
HERE IS WHAT YOU DO
- Squeeze the lemons into a small bowl
- Use the cotton swabs to ‘write’ a message on the paper with the lemon juice
- Leave the paper lying flat so the ‘ink’ can dry
- When the ‘ink’ is dry, take the paper to a dark or semi-dark room with a lamp in it
- Turn the lamp on and hold the paper close to the light bulb in the lamp
- Read the message you wrote on the paper
WHAT JUST HAPPENED
Acid changes everything it touches. When it touches paper, it burns the paper; turning it brown.
Because the acid in a lemon is mild, you cannot see burns on the paper without holding it up to the light.
TRY THIS TOO
- Do this experiment using apple juice, orange juice, and grape juice. Were the results different? How were they different?
- Do this experiment using vinegar. Were the results different? How were they different?
- Do this experiment using dark-colored paper. Were the results different? How were they different?
- Do this experiment using milk. Were the results different? How were they different?
WHAT YOU LEARNED BY DOING THIS EXPERIMENT
- Acid changes a surface.
- Heat helps acid change a surface it touches.
- Some acids are stronger than others.
- An element is a chemical with one type of atom.
- A compound is made up of two or more elements.