Chemical Reactions By: Lauren Busch & Sarah Nguyen
Chemical Reactions • Chemical reactions are involved in photosynthesis and are necessary to sustain life. • Chemical reactions happen all around us. • Not all chemical reactions happen in living things. • All chemical reactions, whether simple or complex, involve changing substances. • As reactants are converted to products, bonds are broken and new bonds are formed. • The old atoms are not destroyed and new atoms are not created. The same atoms are just arranged differently.
There are different ways to tell if a chemical reaction is occurring. Here are some ways: 1. A temperature change. 2. A color change. 3. A precipitate is formed. 4. A gas is given off. 5. Light is given off. 6. Odor is given off. 7. Sound is given off. If one component is being changed, the other component has to be reduced. All chemical reactions have reactants and products. How to Tell if a Chemical Reaction is Occurring
Reactants & Products Reactants are what change into one or more substances. These are what come first in the chemical equation. They are separated with an arrow. Products are the outcome of the reaction which is what you see on the right side of the arrow.
Writing Chemical Equations • You can show the reactants and products by writing a word equation. Steps to writing a Chemical Equation… 1.) Write the reactants on the left 2.) Each reactant(s) is separated by a “+” 3.) The product(s) will be on the right 4.) → the arrow means “yield” or “reacts to produce” Reactants → Products 5.) This statement describes the reaction.
Examples Iron (III) Oxide is formed when Iron reacts to Oxygen. It is written as: Iron + Oxygen → Iron (III) Oxide Water is formed by the explosive reaction between Hydrogen and Oxygen. This chemical reaction is written as: Hydrogen + Oxygen → Water
Write the chemical equation for “Hydrogen Peroxide reacts to produce Water and Oxygen gas.” Hydrogen Peroxide → Water + Oxygen Let’s Try It!
Keep Going! • Identify the reactants. • Identify the product. Sodium and Chlorine Sodium Chloride
Diagrams Propane and Oxygen gas REACTS TO PRODUCE Carbon dioxide, Water, and heat and light.
Web Pages to Visit • http://www.chem4kids.com/files/react_intro.html • http://www.neok12.com/Chemical-Reactions.htm • http://www.sciencekids.co.nz/
HOMEWORK! Label the reactants & products! 1.) When baking soda (Sodium hydrogen carbonate) is heated it decomposes, forming sodium carbonate, carbon dioxide, and water. Reactants: _______________________________________________________ Products: ________________________________________________________ 2.) Water is formed by the explosive reaction between hydrogen and oxygen. Reactants: __________________________________________________________ Products: __________________________________________________________ 3.) KClO3→ KCl + O2 Reactants: _________________________________________________________ Products: __________________________________________________________