Basic Concepts in Chemistry

chemical any substance that takes part in, or occurs as a result of, a chemical reaction All matter can be considered to be chemicals or mixtures of chemicals.

chemical reaction a rearrangement of atoms such that what you end up withproducts differs from what you started withreactants

methane + oxygen + H 2 O(g) carbon dioxide O 2 (g)CO 2 (g)CH 4 (g)+ water+ 22 Combustion of a Hydrocarbon

NaOH(aq) water Na(s)H 2 O(l)H2(g)H2(g)2 sodium 22 hydrogen sodium hydroxide

Law of Conservation of Mass total mass = total mass of reactantsof products R mass = P mass

Black Snake Demonstration The Law of Conservation of Mass total mass of reactants = total mass of products During chemical reactions, no measurable change in total mass occurs. Dehydration of sugarDehydration of sugar with the addition of sulfuric acid. Sugar H 2 SO 4 Click for Video

Basic Concepts in Chemistry sodium + water hydrogen + sodium hydroxide 2 Na(s) + 2 H 2 O(l) H 2 (g) + 2 NaOH(s) Lets visualize whats happening at the particle level… What happens to the particles during a chemical reaction? They are NOT created or destroyed; they are merely rearranged Is there a change in energy associated with a chemical change? Yes: heat, light, sound - perhaps not easily noticed

2 Na(s) + 2 H 2 O(l) H 2 (g) + 2 NaOH(s) Basic Concepts in Chemistry sodium + water hydrogen + sodium hydroxide Lets visualize whats happening at the particle level… What happens to the particles during a chemical reaction? They are NOT created or destroyed; they are merely rearranged Is there a change in energy associated with a chemical change? Yes: heat, light, sound - perhaps not easily noticed

Synthesis taking small molecules and putting them together, usually in many steps, to make something more complex Photosynthesis Sunlight Carbon Dioxide Water Oxygen Glucose CO 2 + H 2 O O 2 + C 6 H 12 O 6

Episode 3 Episode 3 - Measurement The Foundation of Chemistry World of Chemistry The Annenberg Film Series VIDEO ON DEMAND Accuracy and precision are fundamental properties to modern chemistry. The distinction between the two terms and their importance in establishing measurement standards in commerce and science are explained. (Running Time: 28:38)