By: C4nier

What are Chemical Reactions? A chemical reaction is when two or

more molecules interact and chemical change occurs.

What is Happening During a Chemical Reaction

One or more bonds between atoms or molecules are broken and new ones are formed.

Bonds are broken by the interaction of electrons with each other.

Whenever there is a chemical reaction energy is involved, either it is being given off or taken in during the process.

Law of Conservation of Mass

This law states that mass is neither created nor destroyed in an ordinary chemical reaction.

Meaning that the mass of the product in a chemical reaction will equal the mass of the reactant.

Ex. 1.00g carbon + 5.34g sulfur =6.34g carbon disulfide

Signs of A Chemical Reaction

There are several ways to indicate that a chemical reaction has occurred.

For example, if a precipitate (solid form in a chemical reaction) is formed then you have a chemical reaction.

Exothermic and Endothermic Reactions

Exothermic reactions release energy such as heat, light or sound.

Endothermic reactions are just the opposite of exothermic reactions. Instead of releasing energy the consume or absorb it.

http://chemed.chem.purdue.edu/demos/movies/large_movies/16.2.mov

A thermite reaction using Iron(III) Oxide

http://en.wikipedia.org/wiki/Exothermic_reaction

6 Types of Chemical Reactions Decomposition

Single Displacement

Double Displacement

Combustion

Synthesis

1. Decomposition

Decomposition: When a complex molecule breaks down to make simpler ones.

General form: AB ---> A + B

One example: the electrolysis of water to make oxygen and hydrogen gas.

2 H2O ---> 2 H2 + O2

http://cfs.nrcan.gc.ca/images/5947

2. Simple Displacement

Single Displacement: When one element trades places with another element in a compound.

General form: A + BC ---> AC + B

One example is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas.

Mg + 2 H2O ---> Mg(OH)2 + H2

http://www.usoe.k12.ut.us/CURR/Science/sciber00/8th/matter/images/1REPLACE.GIF

3. Double Displacement

Double Displacement: This is when the cation’s and anions of two different molecules switch places and create two completely different compounds.

General form: AB + CD ---> AD + CB

One example is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate.

Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3

http://www.hempfieldarea.k12.pa.us/webdir/MILLERS/sd%20reaction.png

4. Combustion

Combustion: When oxygen forms with another compound to for water or carbon dioxide.

One example of this type of reaction is the burning of napthalene.

(C10H8 + 12 O2 ---> 10 CO2 + 4 H2O)

http://wildeboer-fitch.wikispaces.com/Media-+Chemical+Rx

5. Synthesis

Synthesis: When two or more simple compounds form to makes a more complicated ones.

General form: A + B ---> AB

One example is the combination of iron and sulfur to create iron (II) sulfide.

(8 Fe + S8 ---> 8 FeS)

http://students.ed.uiuc.edu/ljgriffi/project/grifunit3/SYNTHES.GIF

Bibliography

http://www.chem4kids.com/files/reacts_intro.html

http://wiki.answers.com/Q/what_happens_when_a_chemical_reaction_occurs

http://www.harpercollege.edu/tm-ps/chm/100/dgodambe/thedisk/chemrxn/signs.htm

http://misterguch.brinkster.net/6typesofchemicalrxn.html

http://chemistry.about.com/cs/generalchemistry/a/aa051903a.htm

http://www.mi.mun.ca/users/edurnfor/1100/atomic%20structure/tsld004.htm

http://wildeboer-fitch.wikispaces.com/Media-+Chemical+Rx