CHEMICAL CHANGE SCIENCE 5 2nd quarter .pptx

chemical change science 5

1. CHEMICAL CHANGE SCIENCE 5

2. Chemical change occurs when a new substance is formed. It usually involves heat, burning, or release or gain of energy. You can also know that a chemical change is happening due to the presence or lack of oxygen.

3. CHEMICAL CHANGE IN MATTER Some substances tend to form bubbles, rust, or precipitate when mixed with other elements or compounds. These reactions all signify chemical change occurring in matter.

4. Aside from those changes, the following are the other guides that will help you in recognizing chemical change.

5. 1. TEMPERATURE CHANGE A change in temperature can cause absorption or release of heat. Endothermic reactions are those that absorb heat during the reaction, while exothermic reactions give off heat during the reaction .

6. 1. TEMPERATURE CHANGE Most chemical reactions that cause chemical change undergo exothermic reaction. An example of this is fireworks explosion. Once you light fireworks, heat is released and a new product is formed. Thus, chemical change occurs.

7. 2. COLOR CHANGE Change in color can also be an indicator of chemical change. An example of this is a material made of copper that is exposed to the atmosphere for a long period of time. Copper's original color is reddish brown, but once it reacts with water, oxygen and carbon dioxide, it can turn into green. This is best shown in the Statue of Liberty in New York, USA. From its original copper (reddish brown) shade, it slowly turned into blue-green over the years. This is caused by different chemical reactions happening around it such as oxidation.

8. 3. PRODUCTION OF GAS When gas is released as a result of chemical reaction, o smoke or bubbles are formed. These are signs that a chemical change is happening. For example, whenever you mix baking s and vinegar or lemon juice, a gas (carbon dioxide) is produced. reaction between the baking soda and any acidic ingredients in mal a dough produces gas that allows the dough to rice.

9. E XAMPLES OF CHEMICAL CHANGE

10. 1. Cooking an Egg Egg white contains protein. When you fry an egg, the h causes the protein structure to be denatured (destroyed or modified. This permanently changes the texture and appearance of the e making it impossible to turn back into its original form. This make cooking an egg a chemical change.

11. 2. Burning of a matchstick Friction is required to burn a matchstick. Once this happens, combustion occurs. This allows the formation of a new substance. In this case, oxygen gas is formed.

12. 3. Rotting (or browning) of banana When a banana is exposed to air, specifically to the oxygen in the air, oxidation occurs. This turns the fruit into brown.

13. 4. Spoilage of milk An opened canned milk turns into sour or spoiled milk the process of acidification. This is an example of a chemical chan. because once milk is spoiled, it cannot be turned into a fresh one