What is a Chemical Reaction?

• Is burning a twig a chemical or physical change?

• What about dissolving salt into water?• How do I know?

Products vs Reactants

• If I take Glucose and Oxygen and I end up with 2 new compounds, Carbon dioxide and Water

• Write a word equation showing the REACTANTS on the Left and

• PRODUCTS on the Right

Glucose plus Oxygen YIELDS Carbon dioxide and Water

Glucose plus Oxygen Carbon dioxide and Water

Next we turn each name into the correct compound using symbols.

C6H12O6 +O2 CO2 + H2O

• ______________ ___________

• Insert into the blanks REACTANTS or PRODUCTS

We can also add symbols that show the state of matter for each compound.

C6H12O6 (s)+O2 (g) CO2(g) + H2O(l)

s=Solidl= LiquidG=Gas

Practice writing Word Equationsand Chemical Equations

1. If I mix Zinc metal and hydrochloric acid (HCl), I end up with Zinc Chloride plus Hydrogen gas.

2. If I mix Sodium hydroxide with hydrochloric acid, I end up with Sodium Chloride and water

3. Sodium mixed with water gives me Sodium Hydroxide plus Hydrogen gas.

Balancing Equations

• What is the law of Conservation of Mass?

• Mass can neither be created nor destroyed.

http://phet.colorado.edu/en/simulation/balancing-chemical-equations

http://www.youtube.com/watch?v=dExpJAECSL8&feature=related

http://funbasedlearning.com/chemistry/chemBalancer3/default.htm

Start by listing what youAlready have….

Example:H2 + O2 H2O

H 2O 2

H 2O 1

Hints:1) You can balance Polyatomic

Ions in two ways—either each element individually OR as a whole ion (sometimes this is easier)

2) Remember that water can often be balanced as H+ + OH-

More Hints:It is USUALLY easier to work

With the ODD numbered atoms

First as they will have to beMultiplied in order to become

an Even number.

H2 + O2 H2O

H 2O 2

H 2O 1

_Na +_H2O _NaOH + _H2

• We need to determine if there is the same number of atoms of each element on the right as on the left.

• Make a table: (Hint: water can also be written as H+ OH- )

Na 1 Na 1

H 1 H 2

OH 1 OH 1

SO: WE NEED TO BALANCE THE EQUATION.

H OH

_Na +_H2O _NaOH + _H2

Na 1 Na 1

H 1 H 2

O H 1 O H 1

H OH2