Technical Science Introduction to Chemistry by HeG7Ckl

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									    Technical Science
Introduction to Chemistry

     Chemical Equations
Chemical Equations
 In this tutorial you will…
   – Analyze a Chemical Equation
   – Prove a Chemical Equation is Balanced
   – Explain Reasons for Balancing Equations
   – Explore Common Chemical Reactions
                                                 1 of 5
Analyze a
                                                 Home
Chemical Equation
 One of the main functions of chemistry is to
  determine what will happen when substances react.
 A chemical equation is the method used to express
  what happens during a chemical reaction.
 The chemical equation below outlines a familiar
  chemical reaction. What is this telling you?
             2Na + Cl2  2NaCl
 A chemical equation is really just a recipe.
 It tells you the amounts of specific ingredients that
  are required to make a certain amount of a product.
                                                      2 of 5
Analyze a
Chemical Equation
 Let’s take a closer look at that chemical equation.


            2Na + Cl2  2NaCl

   Reactants                                 Products

               you should notice on right equation
               The “results” on that the side
        First,The “ingredients” thethe left side is
                of the equation are called arrow.
           broken into two parts with anthe
                          Reactants
                          Products
        The arrow represents the chemical reaction.
                                                   3 of 5
Analyze a
Chemical Equation
 Identify the reactants and the products in the
  following reactions.
               N2 + 3H2  2NH3
Reactants                                 Products
             BaCO3  BaO + CO2


   MnO2 + 4HCl  MnCl2 + Cl2 + 2H2O
                                                         4 of 5
Analyze a
Chemical Equation
 Let’s take another look at that chemical equation.


             2Na + Cl2  2NaCl

    Coefficients                       Subscripts
              The The small thethis in following us…
               Subscripts tell in number of oftell us…
               You large numbers equationatoms
                 coefficients noticed front tell
                   subscripts the number of the
            TheTheprobablyin this equationatoms or
            Coefficients tell numbersthe numbers
           associatedNabonded symbols arewith
                Two are is inrequired for the reaction.
                that sodiumchemicalCoefficients.
                 formulasareatoms will react for
                      that are called formulas
                        with elemental form.
          moleculesthe chemicaltogether to make the
            (Coefficients of to Subscripts.produce
                One bonded onethe aproducts. of
                arereactants andare not written out.)
                 a singlecalledmoleculemolecule
                      chlorine
                          moleculethe a substance.
                                    of to
    2 Cl atomsCoefficients areformamounts of thechlorine gas.
             (Subscripts of onetheaproducts. itself.
              They determine and substance ofout.)
               Two reactants are not written sodium chloride.
                      1 Cl to make molecule
  1 Na is bonded tomolecules of sodium chloride.
                                                      5 of 5
 Analyze a
                                                      Home
 Chemical Equation
 What do the chemical equations below tell you?
      N2 + 3H2  2NH3 (NH3 is Ammonia)
1 molecule of nitrogen gas reacts with 3 molecules of hydrogen
gas to form 2 molecules of ammonia. Nitrogen and hydrogen
molecules are each formed from 2 atoms bonded together.
Ammonia is formed from 1 N atom bonded to 3 H atoms.
           2MgO + Si  2Mg + SiO2
2 molecules of Magnesium Oxide (each with 1Mg bonded to 1 O)
react with 1 atom of silicon to form 2 atoms of magnesium
and 1 molecule of silicon dioxide (having 1 Si bonded to 2 O)
                                                    1 of 6
Prove a Chemical
                                                    Home
Equation is Balanced
                       Remember: coefficients
 An equation must be balanced to be useful.
                        of 1 are not written out.
 The equation below is not balanced. Can you see
  what is missing?
        2 Na + 1Cl2  2 NaCl
 There are no coefficients in the equation above.
 Coefficients determine the amounts of reactant and
  product.
 The amounts of reactant and product are correct
  when the coefficients make the equation balance.
                                                            2 of 6
Prove a Chemical
Equation is Balanced
 Prove the equation is balanced.

             2Na + Cl2  2NaCl
           Atom          Reactant        Product
             Na               2              2
             Cl               2              2

      The subscriptbalanced of numberequation has the
      Remember, of isCountthe two sodiumnumbers of
      This need toakeepof 2 and because of coefficient on
       We reaction a subscript and lackcoefficientsame
       The This gives athe allthenumber a atoms of
        First:Third: ofbalanced the different elements
         TheSecond: Count the typesof there are
             Coefficient2total chemicaland atoms
                                       the of subscripts,
              lack
                Identify track of lack
                           and of              atoms
      2 onatoms onand types of there are 2molecule ofon
      tellsnumber aretypeatomsthe is one each chloride.
        chlorine,each us that ofatoms sodium atoms
           sodium, tells2 side there of on side. side.
            us that are number ofproduct Na So…
                type each on the this reaction.
                                      equation.
         samethereandinvolved inreactant side.side.
                of tells us that on the product
         and two chlorinemoleculesatoms on both the
            Let’s reactant reactant Na Cl atoms.
               chlorinethe andcoefficients &a table
                   get organized by Sodium
       There are 2 types of atoms: creating 1 subscripts
               Each molecule productand & Chlorine
       You will consider bothhas 1 side.sides. Cl.
                         that contains 2
                                                         3 of 6
Prove a Chemical
Equation is Balanced
 Prove the equation is balanced.
   MnO2 + 4HCl  MnCl2 + Cl2 + 2H2O
           Atom         Reactant       Product
            Mn              1             1
             O              2              2
             H              4              4
             Cl             4              4
                                           2

       4HClSecond:isCountthe one molecule that has
       2H O tells tells us thereofbecause ofmolecule
       First:Third: usup that chemical there on each
         MnClIdentifybalancedare is one MnCl same
            reaction that in of the different are
      ThisMnOtellsbalanced4there twoand atoms thethe
      Remember,usathattrackischlorine equation2hasCl2.
      Chlorine showstotalthere are four molecules& of
       We2needarekeeptheretwonumber atomselements
         There 2 us Count the number of numbers
               tells a the of all products atoms
                2 to                 types
        Clatomsproduct side moleculeto one chlorine.
           number andinvolved in producton So…
           2 tells us this types of theandreaction.
              1 of onand compoundthis on chlorine gas
                type there side bonded2 of each side.
                   each number theatoms side.
                       each is bonded to it
                                        equation.
         same that aretype onof atoms twohasboth the
                 one hydrogen the to chlorines.
                   of oxygen 1       of equation;
        havingmanganese bondedreactant hydrogens.
            Let’s are types hydrogenandsides. H, 2.
            So, get ClMnCl atoms: and Cl a table
             2 from 2 is 1Mn atom creating Oxygen
                    are four of by to Mn, O, Cl
         So will are 4 organizedproduct together. &
      Youthereconsideratomscoefficientstwosubscripts
        So one manganeseand andandtwo &atoms. Cl
         There there fourboth2 bonded 2 four chlorine.
             there reactanthydrogen2 from oxygens.
                with the                      the
                              bonded
                                              4 of 6
Prove a Chemical
Equation is Balanced
 Prove the following reaction is balanced.

         2NO + 2CO  N2 + 2CO2

          Atom      Reactant    Product
            N          2           2
            O           4          4
            C           2          2
                                              5 of 6
Prove a Chemical
Equation is Balanced
 Prove the following reaction is balanced.

    P4O10 + 4HNO3  4HPO3 + 2N2O5

          Atom      Reactant    Product
            P          4           4
            O          22         22
            H           4         4
            N           4         4
                                              6 of 6
Prove a Chemical
                                              Home
Equation is Balanced
 Prove the following reaction is balanced.

      C6H12O6 + 6O2  6CO2 + 6H2O

          Atom      Reactant    Product
            C          6           6
            H          12         12
            O          18         18
                                                1 of 5
Explain Reasons for
                                                Home
Balancing Equations
 You know that a reaction is balanced when the
  coefficients make the number and type of atoms on
  each side of the equation equal.
           2Na + Cl2  2NaCl
 You can also prove whether a reaction is balanced.
 But why is it so important to balance an equation?
 Why wouldn’t you want to write the equation like
  this… Na + Cl2  NaCl
 There are at least three reasons why it is important
  to balance a chemical reaction.
                                                           2 of 5
Explain Reasons for
Balancing Equations
 Look at the unbalanced equation below.

         2 Na + Cl2  2 NaCl

  Na Na            Cl Cl                  Na Cl Na Cl

      The unbalanced equation followingMatter.
           meansLaw of thatwith two of atoms
             The if we startcoefficientssuggestschlorine
              Notice proper are above are in place
              Wherethere areother chlorine of
                      did we two chlorine
     ThisWhen theNow Conservationatoms go?that an
          wetothe reactant that It isdisappeared.
            onmustsomewhere.justcan’tcanchlorine
                 go end equation only not
                  Law of Conservation just disappear.
      It hasTheand thewith twomatter of 1chlorine.
              atom of chlorine atoms ofMatter.
            This law states side but balanced, be
         createdtheThis the product side. in form.
              all or destroyed onlythe law. for.
                     atoms can be changed
                      a very important law
     This leads us to on is againstaccountedinchemistry.
                                                           3 of 5
Explain Reasons for
Balancing Equations
 Look at the partially balanced equation below.

   2Fe + 3H2O                       Fe2O3         + 3 H2

  Fe Fe             O
                  O-Fe-O-Fe-O H-H
             H H              H-H
            O   O             H-H
           H H H H
         AsHydrogen gas is odorless and colorless
          Notice If hydrogens from water on the reactant
            itWhatacoefficientequationof the bonded
               the out, the hydrogen atoms H2
                 in chemical in front is not
     However,turnsthis partially balanced equation
         thattogether to form for youthe product
             would make this anotherare balanced.
              properlyand the oxygenmay miss
              the iron balanced, on balance?
                         but explosive.
       side are not accounted equation product: side.
             not a didpotential Gas (H2atoms overlook.
      That’sWhereproduct you would want to go?
                      Hydrogen product.
                      a those hydrogen )
                                                           4 of 5
Explain Reasons for
Balancing Equations
 What does the unbalanced reaction below tell you?

       2 Na + Cl2                     2 NaCl

       Na Na          Cl-Cl        Na-Cl Na-Cl


       TheAn unbalanced equation isyouare recipe
        Thisamounts equation telltellshow products
          Remember, chemical equations that sodium
             We know the written, us and a recipes.
              reaction, as ingredients are determined
       Balancing the of each substancelikemuch of each
      atoms tell the coefficientsmuch gasassignedproduct
      They (Na) reactyou how the much molecules (Cl2
       but we is required and the ingredients but
              that tells with of that of of each
                don’t know all how ingredients needed.
     reactantby the amountschlorineare each is required)
         doesn’t moleculesof muchis you can expect.
                 when the equation ofchloride to use
                        will of sodium each one
         to form tell you how productbalanced.(NaCl)
          and the amounts be produced.
                                                 5 of 5
Explain Reasons for
                                                 Home
Balancing Equations
 Why is it important to work with a balanced
  chemical equation?
 If an equation isn’t balanced, it implies that atoms
  suddenly appear or disappear. This goes against
  the Law of Conservation of Matter
 If an equation isn’t balanced, you may miss a
  product that is not easily observed.
 An equation is a chemical recipe. If it isn’t
  balanced, it is like a recipe that doesn’t include any
  amounts. It would be useless to try to make
  something from such a recipe.
                                                1 of 16
Explore Common
                                                Home
Chemical Reactions
 A chemical reaction is a recipe that lists amounts
  and type of both reactants and products.
 In this section you will analyze common chemical
  reactions.
 The goal is to give you the background information
  necessary to determine the type of product when
  given the reactants.
 There are seven of these reactions. You have
  already had experience with some of them.
 The following slides will present each of these
  common chemical reactions.
                                                          2 of 16
Explore Common
Chemical Reactions
 Salt Formation

       Metal + Nonmetal  Salt
         2 Na + Cl2  2 NaCl

        4 Fe + 3 O2  2 Fe2O3

        Metals metal objects must be protected from
         Metalscombine with nonmetals is of reaction.
          Most combining with oxygen toalso salts.
                  a the specific of this type form
        There isIn special case example above, called
             oxygen example shown nonmetal)
        corrosion orso this reaction doesn’t occur.
            Metals with Oxygen This reactionIII Oxide.
            reacts react with Oxygen (a Iron with
       IronA specificoxidation.isto form above can be a
          costly one because degrades metalrust.
           sodium metala Metal Oxide (a as objects.
              is to form reacting with metal objects.
                 one is commonly known salt)
         This Whichreason for paintingchlorine gas.
                                                         3 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
  listed below.

        2 Mg + O2  2 MgO
        Metal + Nonmetal     Salt
                (Oxygen)   (Metal Oxide)


             The chemical the salt that forms
               In this is Magnesiumismetal.
                 Mg (magnesium) is balanced
          The productcase, equation aOxide (MgO)
             Mg takes coefficients nonmetal. –2.
                  O2 will be +2is a shown above.
                     (oxygen) charge &
              with the on a a metal oxideO is
          So one Magnesium nonmetals to Oxygen.
               combine with balances oxygen.
         Metalsbecause the nonmetal is one form salts.
                                                          4 of 16
Explore Common
Chemical Reactions
 Base Formation

    Metal Oxide + Water  Base

       Na2O           + H2O  NaOH


        The Basesthat is formedimportant Hydroxide.
          You now a base that a metal oxide is a salt.
              base know is an of compound that
       Rememberrepresenttypeis Sodium class of has
        Na has a +1 charge &hear the term (OH –1
          metal bonded to you OH has –1 charge
        aIt is composed of the Hydroxidea to caustic ).
       compounds. When a metal bondedIonoxygen.or
                Here, alsometal water is (Na+1 a
        alkaline, it isthe NaOH.in reference to ) base.
                  You is know sodium with
       so the formula probablyis (one NaH2O. one OH)
                                                       5 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
  listed below.

        CaO + H2O                      Ca(OH)2
     Metal Oxide + Water               Base


            product is Calcium is a Metal (Ca(OH)
             The chemical equation is balanced
        TheCaO (calcium oxide)Hydroxide Oxide. 2)
            Ca takes onHisO is Water. OH is –1.
                              shown above.
                    as it a2 +2 charge &
        So one Calcium balances two Hydroxide bases.
       Metal Oxides combine with water to form ions.
                                                           6 of 16
Explore Common
Chemical Reactions
 Acid Formation

   Nonmetal + Water  Acid
   Compound
        SO3         +      H 2O                H2SO4

          The acid that is formedare two class that
           Nonmetal compounds compound of
            Acids are another important or Acid.
      Remember an acid is type ofis Sulfuricmore has
          has anonmetals bondedhas a –2 charge.
        Ha Hydrogen ion(s)& heard of various acids;
                 +1 You have SO4 bonded.
       compounds. chargecovalentlyto a nonmetal.
       Here, theYou also know(two H+ trioxide (SO3)
      The formula is H2SO4.the sulfurwith one SO4-2)
                 nonmetal is water is H2O.
           stomach acid, acid rain, battery acid,
         acetic acid (vinegar), citric acid (in fruits),
                ascorbic acid (vitamin C), etc
                                                        7 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
  listed below.

          CO2 + H2O  H2CO3
       Nonmetal       + Water             Acid
       Compound


            (carbon dioxide) is a nonmetal compound.
        CO2The product is Carbonic Acid (H2CO3)
             H takes on H2O charge & CO3 is –2.
                        a +1 is Water.
              The chemical equation is balanced
          Nonmetal compounds combine
                    as it is shown one Carbonate ion.
        So two Hydrogens balance above. with water
                        to form acids.
                                                            8 of 16
Explore Common
Chemical Reactions
 Neutralization

    Acid + Base  Salt + Water

     HCl + NaOH  NaCl + HOH

            The take acids and for an H+1 other
      YouThesaltacidforms from thatis aeachreaction the
       When An pairsreleases which to very stable.
       The A youformsanatom hydrogen this ions. bases
           probably a metal bonded remaining ions.
            H+ ions ofof noticed the OH- ions of
            This is also antacid
                water water replaced nonmetal.
                                        in upset stomach,
             acid pairsthe baseNa+1substances.
               youand really reactive compounds.
                     releases the from theeach
        The makemetal (fromtraded partners.to other.
              Theto H+1atomsdoing is neutralizing
                baseformvery newacid) OH-1base.
                   are
        whatA Thethem istwohydroxide bondsions.your
                           the “neutralize”
             when this is -1 the basefrom the ions
            acid the case is Cl-1 The base acid.
       Thefrom nonmetalwith HCl. the OH from the base.
         H The intheyOHoftenacalled sometimesNaOH.
          ThisThisthe react(from the neutralization.
                reaction of is together, base). is
                    type reaction the H+
     TheButstomach acid bonded to is (the antacid).and
             from thedoubleform orto the (water). the
             called makes H-OH the 2O NaCl
               This a base bonded H to Cl from
                 These ions replacement reaction.
     The Nathe OH- ions bond tightlysalteach other. acid.
                                                        9 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
  listed below.

 2 HCl + Mg(OH)2  MgCl2 + 2 HOH
   Acid     +      Base                  Salt     + Water


               HCl is One product, water, is H-OH
            The other product, thethe salt,a base.
                      an acid. Mg(OH)2 is
               The chemical equation is(MgCl2)
                is(from the acid) takes onbalanced
                   Magnesium Chloride form
          The H Acids react with bases toa +1 charge.
                OH the coefficients)shown –1 charge.
           Thewith (fromSalt+2 charge & Cl is –1.
                         on a base has
              Mg takesa the and Water.a above.
                    So, water is HOH or H2O.
          So, one Magnesium balances two Chlorines
                                                           10 of 16
Explore Common
Chemical Reactions
 Metal Plating

 1st Metal + Salt  2nd Metal + Salt

     Zn + CuSO4  Cu + ZnSO4

          Zinccan seeisis replaced isvery common.
          You ismetal the original metal (theso this
              second metal (product) comes zinc),
                                           copper.
        TheTheThe zincreaction isthecopperfrom the
             This that producedelemental from
                    more in solid
        The salt type ofreactive thanformedform. the
        This The saltreaction nonmetal portion of
          It ismetal place ofwillthe water as salt.
            took theof and the istake place. ions
                type reaction of oftenmetal plating.
                 foundportion the and called a single
       original metalin batteriescopper in the salt. the
                         is dissolved original
          The metal metalis occur if II original 4.
           IfWe it will with Copper salta solution
              copperreplacement reaction.is CuSO
       However,started only Zn. ThetheSulfate &metal
                       here was placed in
                            original salt.
                     sulfate, nothing Sulfate.
             of zincended with Zinc would happen.
         is more reactive than the metal in the salt.
                                                         11 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
  listed below. (Magnesium is more reactive than Silver)

    Mg + 2 AgNO3  2 Ag + Mg(NO3)2
  Metal 1     +      Salt             Metal 2        + Salt


              One product, the metal, ) Silver (Ag)
                  other metal. the salt, is a salt.
             TheMg is aproduct,Ag(NOis is Mg(NO3)2
                                        3 2
                silver was replaced salts ion Mg+2
              Metals can react is now an balanced
                The chemical equation is magnesium.
            TheThe magnesium withby theproducing
               with withits e- nitrate ions Mg+2
             Mgaandthe coefficients shownNO3-1 ion.
                  donated two becoming a above.
                   new salt by replacing the metal.
                The Ag+1 salt. (Magnesium Nitrate)
             forms a newions accepted the e- and
                   went back to elemental form.
                                                         12 of 16
Explore Common
Chemical Reactions
 Combustion
 Organic + Oxygen  Carbon + Water
Compound            Dioxide

    CH4 + 2 O2                    CO2         + 2 H 2O

        This is product for combustion isyour daily.
         Another may be that youDioxideburning.
           One a word is Carbon encounter car,
           Organic compounds contain (CO2
      These fuelsreaction the gasoline in carbon.) the
      The reaction ofallowsequation is gas with ) from
       This reaction organicmethane balanced or the
             The other product ishome, energy
      natural gas chemical isuscompounds (CH4oxygen
                  that heats to Water (H2 oil
            In this case, it your releasecoal,O)
             Oxygen coefficients shown above.)
           towith theis carbon Oxygen and water
              produce simply dioxide Gas (O2
                    organic power your
             food you eat tofuel sources. body.
                    is called combustion.
          The basic reaction is the same for each.
                                                         13 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
  listed below.

     C3H8 + 5 O2  3 CO2 + 4 H2O
   Organic + Oxygen  Carbon
                                              + Water
  Compound            Dioxide

        There is an additional product in combustion
           C H8 reactions and that is energy. reaction
               The chemical an organic compound.
                   products is any combustion
        The 3two(propane) inequation is balanced
            are always coefficientscombustion reaction
            The with oxygen energy is the Water.
               with the Carbon a shown above.
        It reactsproduction ofinDioxide and reason
                       carbon these fuels.
               to formwe burn dioxide and water.
                                                        14 of 16
Explore Common
Chemical Reactions
 Polymerization

   Monomer + Monomer  Polymer

 C2H3Cl + C2H3Cl  -[C2H3Cl]-[C2H3Cl]-


         Small polymerpolymerization islivingcase
         Polymerizationof relatively small molecule.
          A monomer is a putting small used to make
          The molecules is also used by this things.
            process of are bonded together form
        TheThe process that is formed in moleculesis
       createThe monomers in thislike plastics,Starch
        (monomers) together to form of acids. nylon,
        Proteins are polymers groups molecules. are
               synthetic vinyl of amino monomers
                chain of substances example are
       largeramolecules. Thechloridelarger molecules
            It is calledare polymers of C2H3 sugars.
             cellulose called molecules (PVC).
                vinyl chloride polymers.
                         Polyvinyl Chloride
                          is called polymerization.
         and (polymers)styrofoam, etc. simpleCl
                                                           15 of 16
Explore Common
Chemical Reactions
 What product would be formed from the reactants
  listed below.

       C2F4          + C2F4           -[C2F4]-[C2F4]-

     Monomer             +   Monomer          Polymer
 (Tetrafluoroethylene)                         (Teflon)

                         The product is Teflon.
                          C2F4 are monomers.
             It is a polymer of the small C2F4 monomers.
                Monomers combine to form Polymers.
                                                  16 of 16
Name Salts with
                                                      Home
Multivalent Metals
 Write the general reactants and products
Formation
                      Metal + Nonmetal  Salt
of a Salt
Formation            Metal Oxide + Water  Base
of a Base
Formation         Nonmetal Compound + Water  Acid
of an Acid

Neutralization       Acid + Base  Salt + Water

Metal
                    Metal 1 + Salt  Metal 2 + Salt
Plating

Combustion
                 Organic  + Oxygen  Carbon + Water
                 Compound            Dioxide
Polymerization     Monomer + Monomer  Polymer
    Technical Science
Introduction to Chemistry

    You have Completed
    Chemical Equations

                 Created by John W. Pluemer

								
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