# Chemical Reaction

## Types of Chemical Reaction With Balanced Equation

1. Combination-put together 2 substances combine to make compound (also called "Synthesis").

Rule- Remember that the first step to write the correct formulas. You can still change the subscripts at this point, but not later while balancing.

Scheme- A+B = AB

Ex. w/ Balanced Equation- 2Ca + O2 = 2CaO

2. Decomposition- decompose= fall apart one reactant breaks apart into elements or more elements or compounds.

Rule- We can predict the products if its a binary compound (which means it is made up of only two elements).

Scheme- AB = A + B

Ex. w/ Balanced Equation- 2NaCl = 2Na + Cl2

3.Single Replacement- One element replaces another element.

Rule- We can even tell whether or not single replacement reaction will happen: Because some chemicals are more " active " than other. More active replaces less active.

Scheme- AB + C = AC + B

Ex. w/ Balanced Equation- 3K + AlN = Al + K3N

4. Double Replacement- Two things replace each other.

Rule- Have certain " Driving forces ". There's three driving forces.

A. Solid ( precipitate )

B. Gas

C. Molecular compound

Scheme- AB + CD = AC + BD

Ex. w/ Balanced Equation- Na2S + 2HCl = 2NaCl + H2S

5.Combustion- Normally, a compound composed of only C, H, and maybe O, is reacted with oxygen usually called "burning".

• If the combustion is complete, the products will be CO2 and H2O.

Scheme- C#H# + O2 = CO2 + H2O

Ex. w/ Balanced Equation- 2 C8H18 + 25 O2 = 16 CO2 18 H2O

## Steps how to Write and Balanced a Chemical Equation

• Describe a reaction
• Must be balanced in order to follow the Law of Conservation Of Mass
• Can only be balanced by changing the COEFFICIENTS.
• Has special symbols to indicate the physical state, if a catalyst or energy is required, etc.