In the universe everything changes: the galaxies change, the stars change, planet earth changes, and the atmosphere, the soil, the plants, the animals, everything changes.
In the changes we relate magnitudes, initial state and final state of a thing.
A few examples help you understand:
- movement is a change from the state of rest for a time;
- the temperature changes from one heat level to another over a period of time;
- the length of a pole's shadow varies as the sun's rays do;
- water or alcohol change from liquid to vapor as it is heated over a period of time;
- a candle, a paper, a wood change while burning;
- The gasoline in the car decreases in the tank because it is being consumed by the engine;
- Plants and animals continually change from the moment they originate until they finally die;
- many changes happen when heavy rains produce floods.
How to distinguish between chemical and physical changes.
In physical changes the appearance of substances is altered but not their nature, the substances remain the same.
A chemical change produces a substance that did not exist before. There may be signs of a chemical reaction, such as light, heat, color change, gas formation, odor, or sound.
- Let's experiment in home.
|Experiment||Change produced||As it is called?|
|1.Glass with ice, we leave it for a while at room temperature and we observe it.|
|2. Build a doll out of clay.|
|3. Crumple up a piece of paper.|
|4. Pour a drop of food coloring into a glass of water.|
|5. Let a candle burn for a few minutes|
|6. In a glass of water dissolve bicarbonate and add a few drops of lemon.|
Gracias por leer y comentar