1 / 16

Today’s Agenda….

Today’s Agenda…. Bellringer: Explain why melting silver is a physical change. Give as much evidence as possible. Discuss tests Discuss assignments Notes on Chemical Reactions. State Changes. Physical change The substance remains the same It can be reversed Moo Glue? A state change?

Télécharger la présentation

Today’s Agenda….

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Today’s Agenda…. • Bellringer: Explain why melting silver is a physical change. Give as much evidence as possible. • Discuss tests • Discuss assignments • Notes on Chemical Reactions

  2. State Changes • Physical change • The substance remains the same • It can be reversed • Moo Glue? A state change? • It is not a state change because you are putting two liquids together and they react to form a solid • The solid is a new substance • This cannot be easily reversed

  3. Review • What is a chemical change? • Creates a new substance • Not easily reversed • What are some clues that a chemical change has taken place? • Change in color, odor, sound • Release or absorb heat or light • Produce a gas or solid

  4. Chemical Reactions • When you observe a chemical change, a chemical reaction has taken place • Let’s look at some examples! • Create an input/output chart!

  5. Iron Rusting • Look at the before (right) and after (left). • Why does the balloon look the way it does? • What has happened?

  6. Baking Soda and Vinegar • Think about the before and after. • Why did the balloon look the way it did? • What has happened?

  7. Roasting a Marshmallow

  8. An Apple Rotting

  9. Baking Bread Why is this not just a change of state?

  10. What do these all have in common? • Law of conservation of mass • During a chemical OR physical change matter cannot be created or destroyed.

  11. Law of Conservation of Mass • Chemical reactions are represented by symbols and formulas • The symbols come from the periodic table • The numbers tell you how many particles are in the substances • Examples: • O2 • H20 • 3CaCl • 2CO2 • If there is a large number in front you must multiply the small number by that one!

  12. Law of Conservation of Mass • In a chemical reaction you have products (what you start with) and reactants (what you end up with). • Reactants are on the right, products are on the left • The mass must be the same on both sides • The number and type of particles must be the same on both sides

  13. Law of Conservation of Mass • If my reactants have a mass of 45 grams, what will the mass of my products be? • If I have 10 particles that make up my reactants, how many particles will make up my products?

  14. Example: • Iron Rusting • 4Fe + 3O2 2Fe2O3 • None of the particles are lost, they are just rearranged to form new substances!

  15. Energy in Chemical Reactions • Every chemical reaction involves a change of energy • Release energy or absorb energy • This energy is usually in the form of heat • If it releases energy it is called an exothermic reaction • A candle burning

  16. Energy in Chemical Reactions • If it absorbs energy it is called an endothermic reaction • Baking a cake • An emergency ice pack

More Related