C HEMICAL R EACTIONS ! By: LoudElectronicFerocious

Y OU R EALLY S HOULD K NOW T HIS  Reactants The substance that is reacting.  Products The substance that is formed.  Valence Electrons Reactions are all due to the number of valence electrons. Noble gases do not react because they already have eight valence electrons. Visionlearning.com/library/module_viewer.php?mid=54

T YPES OF C HEMICAL R EACTIONS In a chemical reaction, matter is not destroyed nor created in any regular reaction, so says the law of conservation of mass. More simply put, the mass of the product is always equal to the mass of the reactants. ers/edurnfor/1100/atomic %20structure/tsld004.ht m images.encarta.msn.com/xrefmedia/sharemed /targets/images/pho/t046/T046403A.jpg

T YPES OF C HEMICAL R EACTIONS  Synthesis Reaction- Two or more substances combine to make a more complex substance. Example- Simple hydrogen and simple oxygen make water.  Decomposition Reaction- Complex substances break into simpler parts. Decomposition is the opposite of synthesis. Example- Water breaking down into hydrogen and oxygen.

T YPES OF C HEMICAL R EACTIONS ( CONTINUED )  Single Replacement Reaction- A single, uncombined element replaces another element in a compound. Example- When zinc combines with hydrochloric acid and replaces hydrogen.  Double Replacement Reaction- Parts of two compounds switch places to form new compounds. Example- Silver nitrate combines with sodium chloride makes two new compounds because sodium switched with silver. Usoe.k12.ut.us/CURR/Science/sciber00/8 th /matter/sciber/chemtype.htm

T YPES OF C HEMICAL R EACTIONS ( CONTINUED )  Combustion Reaction- When all substances are combined with oxygen. Combustion produces carbon dioxide and water. It is also commonly known as burning. Example- Methanol burning shows a combustion reaction. C x H y + O 2 --> CO 2 + H 2 O Library.thinkquest.org/2923/react.html

C HEMICAL F ORMULAS  Synthesis To tell if a reaction is synthesis, the formula has to have two or more reactants, and only one product.  Decomposition To tell if a reaction is decomposition, there must be one reactant that decays into two products.  Single Replacement To tell if a reaction is single replacement, there must be two reactants and two products, and one of the reactants must have taken the place of another in a bond.

C HEMICAL F ORMULAS ( CONTINUED )  Double Replacement To tell if a reaction is double replacement, there must be two reactants and two products, and two of the reactants must switch places to turn into the product.  Combustion To tell if a reaction is combustion, the reactant must be combined with oxygen to make the product.

S IGNS OF C HEMICAL R EACTIONS crofluid%20bubbles.jpg

S IGNS OF C HEMICAL R EACTIONS  Color Change When a piece of metal rusts, the color changes from silver to a reddish- brown.  Change in Temperature When a chemical produces or loses any heat or energy.

S IGNS OF A C HEMICAL R EACTION ( CONTINUED )  Change in Form When matter changes shape or appearance. For example, burning paper.  Formation of a Precipitate When a solid is formed that differs from the reactant. Usually they are ionic compounds to form insoluble product.

S IGNS OF A C HEMICAL R EACTION ( CONTINUED )  Decomposition of Organic Matter When an organic material breaks down. Two examples could be rotting logs or food.  Formation of a Gas When a gas is created, usually as bubbles. Ansers.yahoo.com/question/index?qid= AAsxvbW 9mrottinglograttraymarsh.jpg

E XOTHERMIC R EACTIONS  Exothermic Reactions When newly bonded atoms have a lower chemical energy than the atom before being bonded. This means more energy exists to produce a light or heat. Most reactions are exothermic. al.html al.html Examples: A thermite reaction using Iron(III) Oxide (right) Adding water to anhydrous copper(II) sulfate. es_of_exothermic_reactionshttp://en.wikipedia.org/wiki/Exothermic_reaction#Exampl es_of_exothermic_reactions.

E NDOTHERMIC R EACTION  Endothermic Reaction When reactants have less energy than the products, so more energy, usually heat, is needed. Usually described as a “cold reaction” Nationmaster.com/encyclopedia/Endothermic-reaction Example: mixing sodium and chlorine to make table salt. jchemed.chem.wisc.edu/.../MAIN/ENDO2/PAGE1.HTM

T HE R OLE OF E NERGY  All reactions also need two reactants, which start the reaction.  Potential energy is stored energy. Chemical potential energy is stored in the bonds of atoms and atoms that keeps these particles held together.  Every chemical reaction comes with an energy that must be overcome so the reaction can actually take place. This is the activation energy, or midnight energy. It was introduced in 1889 by a Swedish man named Svante Arrhenius. Simply, it is the minimal energy need for the reaction to take place.

Bibliography “Chemical Reactions” Visionlearning.com/library/module_viewer.php?mid=54 “The Law of Conservation of Mass” “Types of Reactions” Usoe.k12.ut.us/CURR/Science/sciber00/8 th /matter/sciber/chemtype.htm “Combustion” Library.thinkquest.org/2923/react.html “What are the Signs of a Chemical Reaction?” “Chemical Reactions and Potential Energy” “Examples of Exothermic Reactions” “Exothermic and Endothermic Reactions” “What is the Role of Energy In a Reaction?” “Potential Energy” “Activation Energy”

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