Chemical Reactions Ashton Brown Period 1-2

About Chemical Reactions Chemical reactions occur when a substance undergoes a chemical change. All chemical reactions involve a change in substances and a change in energy.

Chemical Equations A chemical reaction is described by a chemical equation which states what the chemical starts off as, the reactant, and the result of the change, the product. The arrow in the equation shows the change from reactant to product. Ex.: Carbon+Oxygen Carbon dioxide C+O2(Reactant) CO2(Product)

More About Chemical Reactions The mass of the reactants and products are equal, as stated by the law of conservation of mass: mass is neither created nor destroyed in a chemical reaction.

Synthesis Reactions This reaction is when two or more substances react to form a single substance. Either a compound or element can be a reactant, but the product is always a compound. A synthesis reaction is like when you put together berries and cream and you get berries & cream. When written out in symbol form it will look like A+B AB Ex.: 2NA+Cl2 2NACl

Decomposition Reactions This is a reaction where a compound is broken down into two or more simpler substances. The reactant must be a compound and the products may be elements or compounds. A decomposition reaction is like when you take an oreo and separate its layers. You get three different parts, the two cookies and the cream. The formula is written out like so: AB A+B Ex.: 2H2O 2H2+O2

Single Replacement Reactions This is a reaction in which one element takes the place of another element in a compound. An analogy of a simple reaction is a piece of cake and ice cream to a piece of ice and cake cream. The format of this formula is A+BC B+AC Ex.: 2K+2H2O H2+2KOH

Double Replacement Reactions A double replacement reaction is when two different compounds exchange positive ions and form two new compounds. This kind of reaction is like nail polish and hair dye that becomes nail dye and hair polish. This formula is written like AB+CD AD+CB Ex.: H2CO3 CO2+H2O

Pictures Cited http://school.discoveryeducation.com/teachers/chemical_reactions/gallery/freeimagebig.jpg http://www.dkimages.com/discover/previews/857/35080206.jpg http://stud4.tuwien.ac.at/~e0425252/blog/spps/3grosz.jpg http://www.rsc.org/images/b601111j-250_tcm18-55258.jpg http://www.dailygalaxy.com/photos/uncategorized/2007/06/11/rna_origins_of_life.jpg http://farm1.static.flickr.com/9/76060472_8c523ee39c.jpg?v=0