Introduction to chemical reactions/balancing

1.) Conservation of Mass

a.) Matter cannot be created nor
destroyed

b.) The mass on the left side (reactants)
MUST EQUALthe right side (products).

2.) Chemical Reaction Vocab

a.) Shown by chemical equations

4 Cu (s) + 1 O2 (g) → 2 Cu2O (s)

coefficients

subscripts

state of matter

2b.) Sides?

2Fe + O2 🡪 2FeO

Reactant(s)

Product(s)

“Rust”

2c.) Symbols in Equations

🡪

🡪🡪

s

L

g

aq

yields, produces, reacts to form

reversible reaction

heat is added

solid

Liquid (pure substance, Ex:Water)

gas

aqueous (dissolved in water)

3.) Why do Reactions Have to

be Balanced?

a.) To show that the law of conservation
of mass is satisfied.
b.) To know the proportions (amount of) the
elements and compounds react in.

4.) Balancing Equations Using

Atom Inventory

Zn + HBr → ZnBr2 + H2
_

a.) You can never change subscripts (determine bonding), only
coefficients (determine how many).
b.) You must change in the equation (on top) before adjusting
numbers below. The “inventory” (bottom) is just for counting.

_

_

_

Zn

H

Br

5.) Determine Atom “Inventory”

Li + AlCl3→ LiCl + Al

_

You must change in the equation (on top)
before adjusting numbers below. The
“inventory” (bottom) is just for counting.

_

_

_

What
elements do
we have?

6.) You Try!

NaF + O2→ Na2O + F2
_

You must change in the equation (on top) before adjusting
numbers below. The “inventory” (bottom) is just for counting.

_

_

_

7.) You Try!

Ga + CaBr2→ GaBr3 + Ca

_

You must change in the equation (on top) before adjusting
numbers below. The “inventory” (bottom) is just for counting.

_

_

_

End of Balancing