Chemical Chemical ReactionsReactions

Lauren Simonton

What are chemical reactions?

• Chemical reactions occur when bonds are formed or broken between molecules. Reactants are the substances that undergo a change in the chemical reaction. The products are the new substances that are a result of the chemical reaction.

Chemical Equations

• Chemical equations help show what is present before and after the reaction takes place.

• A chemical equation is a representation of a chemical reaction in which the reactants and products are expressed as formulas.

We use chemical equations to summarize the process of chemical reactions into a word equation

Chemical equations need to be balanced in order to show that mass is conserved during a reaction.

The law of conservation of matter states that mass is neither created or destroyed in a chemical reaction.

• Reactant: a substance that undergoes a change in a chemical reaction.

• Products:new substances formed as a result of a chemical reaction.

• In a chemical formula the arrow means that the reactants are producing that exact product.

C + O2 CO2

Synthesis Reactions• A reaction in which two or more substances react to form a

single substance.The reactants may be either elements or compounds. The product is always a compound.

• Brownies + cream cheese Cream cheese brownies

• A + B AB

• Hydrogen and oxygen combine to form water.

2H2 + O2 2H2O

Decomposition Reactions

• A reaction in which a compound breaks down into two or more simpler substances.

• Milk Solids + Water

• AB A + B

• When making cement a mixture of clay and limestone is heated and the heat cause the calcium carbonate in the limestone to decompose into lime and carbon dioxide.

CaCO3 CaO + CO2

Single-Replacement

• Reaction in which one element takes the place of another element in a compound.

• A person reading a book switches to a different book.

• A + BC B + AC

The copper replaces the silver in silver nitrate to form copper (II) nitrate.

• Cu + 2AgNO3 2Ag + Cu(NO3)2

Double-Replacement

• Reaction is where two different compounds exchange positive ions and form two new compounds.

• Formal dancing and two couples switch partners.

• AB + CD AD + CB

• Lead(II) nitrate and potassium iodide. Are color less but when mixed a yellow precipitate forms.

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

Work cited• http://images.google.com/imgres?imgurl=http://

www.chemistryexplained.com/images/chfa_01_img0184.jpg&imgrefurl=http://www.chemistryexplained.com/Ce-Co/Chemical-Reactions.html&usg=__c2F2V_MJuJWMDuhZNnqV1hPBQ_8=&h=450&w=311&sz=16&hl=en&start=4&tbnid=0XOd7QoP-1i8yM:&tbnh=127&tbnw=88&prev=/images%3Fq%3Dchemical%2Breactions%26gbv%3D2%26ndsp%3D18%26hl%3Den%26sa%3DN

• http://www.chemistryland.com/CHM130W/TypesReactions.jpg

• http://upload.wikimedia.org/wikipedia/commons/a/a0/Hydrochloric_acid_ammonia.jpg

• http://www.unitednuclear.com/tree.jpg