chapter 11 chemical reactions. note taking tips! paraphrase, paraphrase, paraphrase! use symbols,...

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Chapter 11 Chemical Reactions

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  • Chapter 11Chemical Reactions

  • Note Taking Tips!Paraphrase, paraphrase, paraphrase!Use symbols, arrows, pictures, and abbreviations whenever possible.Write side notes to help you remember concepts.

  • What is a chemical reaction?Occur every minute of every day!When one or more reactants change into one or more products. Characterized by the breaking of bonds in reactants and formation of bonds in products

  • Law of Conservation of MassIn any physical or chemical reaction, mass is conserved; mass can be neither created nor destroyed

  • Chemical ReactionsChemical reactions are described by chemical equations. Skeleton Equation: chem equation that doesnt indicate relative amounts of reactants and products. Fe + O2 Fe2O3

    ReactantsProducts

    It needs to be balanced!!!

  • Draw this one

    It means the reaction is reversible

  • Catalyst: a substance that speeds up the reaction but is not used up in a reaction. Neither a reactant nor a productWritten above arrow in chem equation. MnO2H2O2(aq) H20(l) + O2(g)

  • Balancing ActBicycle scenario

  • Balancing Chemical EquationsA chemical reaction where each side of the equation has the same number of atoms of each element and mass is conserved.

    Fe + O2 > Fe2O3

  • Steps to Balancing1. Count atoms on each side. Count polyatomic ion as one unit if it appears unchanged on right. 2. Balance elements one at a time using coefficientsBalance elements that appear only once 1stNever change subscripts3. Check work and make sure all coefficients are in lowest possible ratio.

    H2 + O2 > H2O

  • Lets try some!

  • Lets try some!_____ S + _____ O2 --> _____ SO2

    _____ Na+ _____ O2 --> _____ Na2O2

    3. _____ Hg + _____ O2 --> _____ HgO

    4. _____ Ag2O --> _____ Ag + _____ O2

  • Lets try some!

  • Practice

  • Practice

  • 11.2 Types of Chemical ReactionsConcept map5 general typesCombinationDecompositionSingle-replacementDouble-replacementCombustion

  • Concept map instructionsGet basic definitionWrite at least one chemical reactionDescribe the demonstration reaction

  • CombinationWhen 2 or more substances react to form a single new substance.

    2Mg + O2 > 2MgO

  • DecompositionWhen a single compound breaks down into 2 or more simpler products. 1 reactant, 2 or more productsUsually require heat, light, or electricity to occur.

    2HgO > 2Hg + O2

  • Single-ReplacementWhen 1 element replaces a second element in a compound. 2K + 2H2O > 2KOH + H2

    Look at the switch!

  • Double-ReplacementAn exchange of positive ions between 2 compounds. Usually produces one of the followingA precipitateA gaswaterRemember: positive ions=cations=on left side of a compound

    Na2S + Cd(NO3)2 > CdS + 2NaNO32NaCN + H2SO4 > 2HCN + Na2SO4Ca(OH)2 + 2HCl > CaCl2 + 2H2O

  • CombustionWhen an element or compound reacts with oxygen, it produces energy in the form of heat and light. Oxygen is always a reactantThe other reactant is often a hydrocarbon (something with hydrogen and carbon)CH4 methaneC3H8 propaneC4H10 butaneC8H18 gasolineCO or CO2 can also be products

    2C8H18 + 25O2 > 16CO2 + 18H2O

  • Practice!

  • Your TaskDissecting a chemical reaction