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__ Vocabulary __ __Chemical Reaction –__ a change in which one or more substances are converted into new substances __Reactant –__ substances that react __Product –__ new substance produced __Chemical equation –__ way to describe a chemical reaction using chemical formulas and other symbols __Coefficient –__ represent the number of units of each substance taking part in a reaction __ Reading Check __ __Pg. 633-__ The total starting mass of all reactants equals the total final mass of all products __Pg. 634-__ For his more accurate explanation of the conservation of mass and for describing a common type of chemical reaction called combustion __Pg. 636-__ Represents the number of units of each substance taking part in a reaction __ Caption Questions __ None __ Self Check __ Identify the reactants and the pructs in the following chemical equation: Cd(NO(3))(2)(aq)+H(2)S(g)  à CdS(s)+2HNO(3)(aq) ~Reactants: Cd(NO(3))(2)(aq)+H(2)S(g) Products: CdS(s)+2HNO(3)(aq) Identify the state of matter of each substance in the following reaction: Zn(s)+2HCl(aq)  à H(2)(g)+ZnCl(2)(aq) ~Solid, aqueous, gas, aqueous Explain why the reaction of oxygen with iron is a problem, but the reaction of oxygen with aluminum is not. ~Oxygen with iron can create rust; damaging structures but oxygen with aluminum will protect the structure Explain the importance of the law of conservation of mass. ~States that the total starting mass of all reactants equals the total final mass of all products. Why do you think the copper patina was kept when the Statue of Liberty was restored? ~Because it remains a strong material and will continue to become blue-green. When making soap, if 890g of specific fat react completely with 120g of sodium hydroxide, the products formed are soap and 92g of glycerin. Calculate the mass of soap formed to satisfy the law of conservation of mass. ~890+120  à 92+918 110-92= 918 of soap __ Vocabulary __ __Balance chemical equation-__ same number of atoms of each element on both sides of the equation __ Reading Check __ __Pg. 639-__ By adding them to either side making it even __ Caption Question __ None __ Self Check __ Describe two reasons for balancing chemical equations. ~To represent the equation correct and to have the same number of atoms of each element on both sides of the equation. Balance this chemical equation: Fe(s)+O(2)(g)  à FeO(s). ~2Fe+O(2)  à 2FeO Explain why oxygen gas must always by written as O(2) in a chemical equation. ~Because it’s required for a balanced chemical equation. What coefficient is assumed if no coefficient is written before a formula in a chemical equation? ~ 1 is the coefficient Explain why the sum of the coefficients on the side of a balance equation does not have to equal the sum of the coefficient on the product side of the equation. ~Because you also have to take in count the subscripts, so the coefficients may differ. Balance the equation for the reaction: Fe(s)+Cl(2)(g)  à FeCl(3)(s) __ Vocabulary __ __Combustion reaction-__ occurs when a substance reacts with oxygen to produce energy in the form of heat and light __Synthesis reaction-__ two or more substances combine to form another substance. The generalized formula for this reaction type is as follows: A+ B  à AB  __Decomposition reaction__- one substance breaks down, or decomposes, into two or more substances. The general formula for this type of reaction can be expressed as follows: AB  à A+B __Single-displacement reaction-__ one element replaces another element in a compound. Described by general equation: A+BC  à AC+B __Double-replacement reaction__- positive ion of one compound replaces the positive ion of the other to form two new compounds. Takes place if a precipitate, water, or a gas forms when two ionic compounds in solution are combined. __Precipitate-__ an insoluble compound that comes out of solution during this type of reaction. Generalized formula for this type of reaction is as follows: AB+CD  à AD+CB __Oxidation__- describe the loss of electrons __Reduction-__ describe the gain of electrons __ Reading Check __ __Pg. 642__- A=BC  à AC+B __ Caption Questions __ __Pg. 642__- Because the amount is moving from side to side __ Self Check __ Classify each of the following reactions ~a. synthesis reaction b. single displacement c. decomposition reaction Describe what happens in a composition reaction. ~ A substance reacts with oxygen to produce energy in the form of heat and light. Explain the difference between synthesis and decomposition reactions. ~Synthesis: two or more become one; decomposition: one becomes two or more Determine if zinc will displace gold in a chemical reaction and explain why or why not. ~No, because zinc is more active than gold Describe one possible economic impact of redox reactions. How might that impact be lessened? ~May cause rust on economic objects, we can lessen these chemical reactions with control. ~3Fe+4H(2)O  à Fe(3)O(4)+4H(2) ~3SO(3)+2H(2)O  à 2H(2)SO(4) __ Applying Math __ __ Vocabulary __ __Exergonic reaction-__ chemical reactions that release energy __Exothermic reaction-__ when the energy given off in a reaction is primarily in the form of heat __Endergonic reaction-__ when a chemical reaction required more energy to break bonds than is released when new ones are formed __Endothermic reaction-__ when the energy needed is in the form of heat (physical change) __Catalyst-__ a substance that speeds up a chemical reaction without being permanently changed itself __Inhibitor-__ used to slow down a chemical reaction __ Reading Check __ __Pg. 648-__ Because a log fire gives off heat __Pg. 650-__ To speed up the formation __ Caption Questions __ __ None __ __ Self Check __ Classify the chemical reaction photosynthesis, which required energy to proceed, as endergonic or exergonic. ~Endergonic Explain why a catalyst is not conisdiered a reactant or product in a chemical reaction. ~Because if doesn’t change the amount of product produced, just the rate of production Explain why crackers containing BHT stay fresh longer than those without it. ~BHT prevents spoilage in foods Classify the reaction that makes a firefly glow in terms of energy input or output. ~Exergonic reactions; output To develop a product that warms people’s hands, would you choose a exothermic or endothermic reaction to use? Why? ~Exothermic because it primarily is in the form of heat If an endothermic reaction begins at 26 degrees Celsius and loses 2 degrees Celsius per minute, how long will it take to reach 0 degrees Celsius? ~26/2= 13 minutes About 50 degrees Celsius
 * Chapter 21 – Chemical Reactions **
 * Section 1 – Chemical Changes **
 * Section 2 – Chemical Equations **
 * Section 3 – Classifying Chemical Reactions **
 * __ Section 4- Chemical Reactions and Energy __**