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Chemical Reactions. Lauren Simonton. What are chemical reactions?.
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Chemical Reactions 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