Chemistry 2.1

ChemistryChapter 2 - Section 1

Chemical Formulas & Equations

Monday, July 9, 2012

Physical or Chemical?





Yeast +

Hydrogen Peroxide =

???????


Chemical Reaction?


A process that produces a

chemical change

Chemical Reaction?


Chemical Equations


Chemical Equations


Substances that exist before the reaction begins

Chemical Equations


Substances that exist before the reaction begins

Chemical Equations

Substances that form as a result of the reaction


Describe What is Happening



I use a chemical

equation to know the reactants,

products and proportions

of each substance.





My Chemical Equation can use

words, chemical names,

or formulas.


Using Words

Baking Soda + Vinegar --> Gas + White Solid

Charcoal + Oxygen --> Ash + Gas + Heat


Chemical Names

Acidic Acid + Sodium Hydrogen Carbonate -->

Sodium Acetate + Water + Carbon Dioxide


Chemical Formula’s

CH3COOH + NaHCO3 --> CH3COONa + H2O + CO2

Sodium Hydrogen Carbonate

Acetic Acid

Sodium Acetate

Water Carbon Dioxide


Arrows and Subscript


It’s All a Balancing Act


Conserve That Mass


Conserve That Mass

The mass of the products must be the same as the mass of the reactants in the chemical reaction.


Conserve That Mass

The mass of the products must be the same as the mass of the reactants in the chemical reaction.

Atoms are never lost of created in a chemical reaction; however they do change partners.


Conserve That Mass


Let’s Try

Tarnishing silver....

Ag + H2S --> Ag2S + H2

SilverHydrogen sulfide

Silver Sulfide Hydrogen


Let’s Try


Let’s Try

Na + AlCl3 --> NaCl + Al KBr + Cl2 --> KCl + Br2

H2O2 --> H20 + O2


Energy in a Chemical Equation


Energy is often released or absorbed during a chemical reaction.

Energy in a Chemical Equation


Energy Released


Energy Released

Where does this energy come from?


Energy Released

Where does this energy come from?

You have to think about the chemical bonds of the reactants and the products, in order to answer this question.


Energy Released


Energy Released

When energy is released, the products are more stable, and their bonds have less energy than those of the reactants.


Energy Released

When energy is released, the products are more stable, and their bonds have less energy than those of the reactants.

The extra energy is released in different forms: light, sound, thermal energy.


Energy Absorbed


Energy Absorbed

When energy is absorbed, the reactants are more stable, and their bonds have less energy than those of the products.


Energy Absorbed

When energy is absorbed, the reactants are more stable, and their bonds have less energy than those of the products.

The extra energy needed to form the products can be supplied in the form of electricity, light, sound, thermal energy.


Energy Released

2H2 + O2 --> 2H2O + energy


Energy Released

2H2 + O2 --> 2H2O + energy

2H2O + energy --> 2H2 + O2


Energy Released

2H2 + O2 --> 2H2O + energy

Energy Absorbed

2H2O + energy --> 2H2 + O2


When thermal energy is gained or lost, special

terms are used….



terms are used….



terms are used….



terms are used….

Absorb thermal energy

Release thermal energy


Endothermic or Exothermic Absorb or ReleaseQuickly or Slowly


Adding ENERGY to the equation


Finished!


Technology

Chemistry 2.1