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Published byAmy May Modified over 9 years ago
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I can read and understand the information contained within a chemical reaction
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Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes. In a given reaction …. Symbols represent elements (H) Chemical formulas describe compounds (Al 2 O 3 )
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reactantsproducts ◦ Chemical equations show the conversion of reactants (on the left of the arrow) into products (on the right of the arrow). “+” sign separates molecules on the same side The arrow is read as “yields” Example C + O 2 CO 2 This reads “carbon plus oxygen yields carbon dioxide”
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The charcoal used in a grill is basically carbon. The carbon reacts with oxygen to yield carbon dioxide. The chemical equation for this reaction, C + O 2 CO 2, contains the same information as the English sentence but has quantitative (numerical) meaning as well.
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Chemical reactions depict the kind of reactants and products in a given chemical reaction and their relative amounts. Reactants are “what goes in” and Products are “what comes out!” 4 Al + 3 O 2 → 2 Al 2 O 3 The numbers in the front are called coefficients.
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The coefficient in front of a given element in an equation can stand for a representative particle (one piece) of the substance OR a mole of the substance 4 Al + 3 O 2 ---> 2 Al 2 O 3 4 atoms of aluminum plus 3 molecules of oxygen gas yield two molecules of aluminum oxide OR 4 moles of aluminum plus 3 moles of oxygen gas yield two moles of aluminum oxide
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(l) “liquid”; this indicates that a chemical is in liquid form. EX: H 2 O (l) (aq) “aqueous”; this indicates that a chemical is dissolved. EX: NaCl (aq) (g) “gaseous”; this indicates that a chemical is in gaseous form. EX: CO 2(g) (s) “solid”; this indicates that a chemical is in solid form. EX: Mg(OH) 2(s) “precipitate”; this indicates that a product is a solid precipitate. EX: CaCO 3 “delta” or “heat”; this symbol over the yields sign indicates that heat is added to move the reaction along.. EX: ↑ “gas”; this indicates that a product is formed which is a gas, and forms bubbles. EX: H 2 ↑
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I can differentiate between the different types of chemical reactions.
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〉 How does learning about reaction types help in understanding chemical reactions? 〉 You can use patterns to identify kinds of chemical reactions and to predict the products of the chemical reactions.
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There are five types of chemical reactions we will talk about: 1.Synthesis reactions 2.Decomposition reactions 3.Single replacement reactions 4.Double replacement reactions 5.Combustion You need to be able to identify the type of reaction
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Synthesis reactions occur when two substances (generally elements but sometimes compounds) combine and form a compound reactant + reactant 1 product A + B AB Example: 2H 2 + O 2 2H 2 O Example: C + O 2 CO 2
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Here is another example of a synthesis reaction
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Decomposition reactions occur when a compound breaks up into the elements or into a few simpler compounds 1 Reactant Product + Product In general: AB A + B Example: 2 H 2 O 2H 2 + O 2 Example: 2 HgO 2Hg + O 2
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Another view of a decomposition reaction:
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Single Displacement Reactions occur when one element replaces another in a compound. A metal can replace a metal OR a nonmetal can replace a nonmetal. element + compound product + product A + BC AC + B (if A is a metal) OR A + BC BA + C (if A is a nonmetal)
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Sodium chloride solid reacts with fluorine gas NaCl (s) + F 2(g) NaF (s) + Cl 2(g) Note that fluorine replaces chlorine in the compound Aluminum metal reacts with aqueous copper (II) nitrate Al (s) + Cu(NO 3 ) 2(aq) Cu (s) + Al(NO 3 ) 3(aq)
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Another view:
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Double Replacement Reactions occur when a metal replaces a metal in a compound and a nonmetal replaces a nonmetal in a compound Compound + compound product + product AB + CD AD + CB
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Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together Example: AgNO 3(aq) + NaCl (s) AgCl (s) + NaNO 3(aq) Another example: K 2 SO 4(aq) + Ba(NO 3 ) 2(aq) KNO 3(aq) + BaSO 4(s)
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Combustion reactions occur when a hydrocarbon reacts with oxygen gas. These always produce CO 2 and H 2 O as products. In order to burn something you need the 3 things in the “fire triangle”: 1) A Fuel (hydrocarbon) 2) Oxygen to burn it with 3) Something to ignite the reaction (spark)
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Examples C 5 H 12 + O 2 CO 2 + H 2 O and 5 6 8
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