Predicting Reactions

Presented byMr. Mark LangellaSTANYS 2006PWISTA.com11/7/06

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Why do the reactions occur?

Gibbs Free Energy drives the Spontaneous reactionsLower PE energyFormation of Stronger BondsGreater Entropy ( Formation of Gases)

Solubility Formation Constant Lose Yourself in Chemical Reactions - Go

ogle Video

Synthesis or Combination Reactions In synthesis or combination reactions, two

or more substances combine together to form a single product.

The general form is A + B C The products must contain only those

elements found in the reactants.

Metal + Nonmetal Salt

Magnesium ribbon is burned in oxygen

Combination or Synthesis Reactions General form

A + B C

In this demonstration 2 Mg + O2 MgO

3 Mg + N2 Mg3N2

The oxygen and nitrogen occur naturally in the

atmosphere O2 is 21% of air N2 is 78% of air

Energy Two types of energy are produced in this

demonstration heat energy Hf MgO = -601.83 kJ/mole

(kiloJoules per mole) this is said to be the ‘heat of formation’ for MgO the negative sign indicates the formation is exothermic

light energy approximately 10% of the energy of combustion occurs

as light in this demonstration more light than any other known reaction

Online Demos

Reaction of Iron and Sulfur http://www.pc.chemie.uni-siegen.de/pci/versuche/pics/anim/fes.mpg Fe + S FeS Reaction of Potassium and Oxygen http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag

e08.htm

Reaction of Lithium and Oxygen http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag

e02.htm Reaction of Lithium and Chlorine http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag

e04.htm Reaction of Sodium and Oxygen http://neon.chem.ox.ac.uk/vrchemistry/FilmStudio/alkalimetals/HTML/pag

e05.htm Reaction of Zinc and Sulfur http://boyles.sdsmt.edu/znsulf/zincsul.htm

Nonmetal + Nonmetal Molecular compounds Reaction of Hydrogen

and Oxygen http://www.chem.uiuc.

edu/clcwebsite/video/Bal2.mov

Rubber tubing

Volumetric flaskcontaining

NaOH and Al

Drying tube

Water bottleclamped onto

a rinstand

Short piece ofPyrex glass tubinginserted into aone-hole stopper

Reaction of Phosphorus and Chlorine

http://boyles.sdsmt.edu/pwithcl/DirksTwo.asx

P4(s) + 10 Cl2(g) 4 PCl5(s)

Oxidation Number Changes

Nonmetal Oxide + Water Oxyacid

Oxy Acid= Contains H+ ions attached to common Polyatomic ion of Nonmetal Oxide plus one more oxygen

Formation of Carbonic Acid

Carbon dioxide and Water- Carbon Dioxide is easily produced by the reaction of sodium bicarbonate and vinegar.

http://boyles.sdsmt.edu/respira/AlexanderCo2Blue.asx

Reaction of Carbon Dioxide and Limewater

http://boyles.sdsmt.edu/respira/Alexander

Co2White.asx

CO2(g) + Ca(OH)2(l) CaCO3(s) + H2O(l)

Metal oxide + water metal hydroxide

Egg Fry

DECOMPOSITION REACTIONS

Substances break down by means of decomposition reactions

The general form of a decomposition reaction is

C A + B Decomposition reactions are the opposite

of combination or synthesis reactions

Decomposition of Metal Carbonate

Heating a metal carbonate always yields the metal oxide and carbon dioxide. MCO3 MO + CO2

Heating the carbonates Most carbonates tend to decompose on heating to give the metal oxide and

carbon dioxde. For example, a typical Group 2 carbonate like calcium carbonate

decomposes like this: In Group 1, lithium carbonate behaves in the same way - producing lithium

oxide and carbon dioxide. The rest of the Group 1 carbonates don't decompose at Bunsen

temperatures, although at higher temperatures they will. The decomposition temperatures again increase as you go down the Group.

Metal Hydrogen Carbonate Decomposition Heating a metal bicarbonate gives the

metal oxide, carbon dioxide, and water. MHCO3 MO + H2O + CO2

Solid Sodium Hydrogen Carbonate is strongly heated

Metal Chlorate Decomposition

Heating a metal chlorate gives the metal chloride plus oxygen.

MClO3 MCl + O2

Burning Gummi Bears http://www.webct.com/service/ViewContent?

contentID=1249557&communityID=858&categoryID=1249537&sIndex=0

Logger Pro Analysis

Decomposition of Ammonium Dichromate http://boyles.sdsmt.edu/dichrom/Ammoniu

mDichromate.asx

(NH4)2Cr2O7(s) Cr2O3(s) + N2(g) + 4H2O(g)

Peroxide Decomposition

Elephant’s Toothpaste Website: http://boyles.sdsmt.edu/tpaste/Cain.asx

Genie in a Bottle Demo Website: http://

boyles.sdsmt.edu/geniebot/genie.htm

Reactions Based on Reduction Potentials EMF Potential

Reduction and OxidationSingle replacement

Cation Replacement

There are two types of single replacement reactions, in one, a metal or hydrogen replaces a positive ion

M0 + A+B- M+B- + A0

Reaction of Sodium and Water

http://boyles.sdsmt.edu/sodwat/SodiumWater.asx

http://www.theodoregray.com/PeriodicTable/Stories/011.2/Videos/SodiumResearch03.html

http://www.theodoregray.com/PeriodicTable/Stories/011.2/Videos/SodiumResearch02.html

Sodium(s) + Water(l) Sodium Hydroxide(aq) + Hydrogen(g)

2Na(s) + 2H2O(l) 2NaOH(aq) + H2(g)

Reaction of Potassium and Water http://www.chem.shef.ac.uk/webelements-moov/K_H2O.mov http://www.theodoregray.com/PeriodicTable/AlkaliBangs/

019_K_doghowls.html Potassium(s) + Water(l) Potassium Hydroxide(aq) +

Hydrogen(g) 2K(s) + 2H2O 2KOH + H2(g) Group I with water video http://video.google.com/videoplay?docid=-213426665480139

2897&q=rubidium+water

Reaction of Zinc and Tin (II) Chloride

http://www.chemtopics.com/lectures/unit02/lecture1/displace.htm

Zinc(s) + Tin (II) Chloride(aq) Tin(s) + Zinc (II) Chloride(aq)

Zn(s) + SnCl2(aq) Sn(s) + ZnCl2(aq) Zinc(s) + Hydrochloric Acid(aq) Zinc (II)

Chloride(aq) + H2(g) Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g) Aluminum and Copper ( II) Chloride

Thermite Reaction 2Al(s)+Fe2O3(s) Al2O3(s)+2Fe(l)

http://boyles.sdsmt.edu/thermite/ThirstrupThermiteClose.asx

http://www2.chemie.uni-erlangen.de/education/medprak/videos/thermit_v.mpg

http://video.google.com/videoplay?docid=-7231843493488769585&q=Reactions&hl=en

Aqueous Redox ReactionsOxidation States of Manganese

Procedure Add 30 ml of a .01 M KMnO4 solution to four small flasks

labeled A , B, N ( Place Tablet 1/10 ml water) To Flask A, Add 10 ml of 3M H2SO4

MnO4- + H+ To Flask B, add 10 ml of 5 M NaOH. MnO4- + OH- To Flask N add nothing. MnO4-

Watch the color changes

To Flask A add .01M NaHSO3 ( Tablet 2) slowly till you get a colorless Mn2+ ion.

MnO4- + 5H++ HSO3

- 3H2O + 2Mn2+ + 5SO42-

To Flask N add .01M NaHSO3 ( Tablet 2)until a brown precipitate forms.

2MnO4- + 3HSO3

- 3SO42- + H++ H2O +MnO2

To Flask B slowly add .01M NaHSO3 ( Tablet 2) until a green solution forms.

2MnO4- + OH-+ HSO3

- 2MnO42- + 2H2O + SO4

2-

The Amazing Purple Drop

Oil Drop Demo I2 + H20 HOI ( aq) + HI ( aq)

Meanwhile I2 + 2e- = 2I-, Eo = 0.54 v

HCHO + 2H+ + 2e- = CH3OH, Eo = 0.19 v

Reactions Driven by

Solubility and Precipitation Formation of Gases ( Increase in entropy) Formation of Water Coordinate Covalent Bond Formation

( Lewis Acid-Base) Formation Constants

Formation of Water

Metal Oxide + an Acid Salt + Water Metal Hydroxide + an Acid Salt + Water (a special type of reaction called

neutralization) Milk of Magnesia Demo

PREDICTIONS BASED ON SOLUBILITY If one or both of the products in the double replacement

reaction is insoluble in water, the reaction will occur. Reaction #1 Lead Nitrate and Sodium Chromate Pb(NO3)2 (aq) + Na2CrO4 (aq) PbCrO4 (s) +

Na NO3(aq) Pb 2+ + CrO42- PbCrO4 (s) Reaction # 2 Silver Nitrate and Hydrochloric Acid AgNO3(aq) + HCl(aq) AgCl (s) + HNO3 (aq)

SOLUBILITY RULES FOR COMMON IONIC COMPOUNDS IN WATER

1. All nitrates, chlorates, and acetates are soluble in water. Silver acetate is sparingly soluble.

2. Most common acids are soluble in water. 3. All common IA, and ammonium compounds are soluble in water. 4. All chlorides, bromides, and iodides are soluble in water except

silver, mercury (I), and lead. HgI2 and HgBr2 are insoluble in water. 5. All sulfates are soluble in water except CaSO4, SrSO4, BaSO4,

PbSO4, Hg2SO4. Ag2SO4 is sparingly soluble in water. 6. All carbonates, phosphates, oxides, and sulfites are insoluble in

water but soluble in dilute acids except the IA and ammonium compounds. 7. The sulfides of all metals are insoluble in water except the IA, IIA,

and ammonium sulfides. 8. All hydroxides are insoluble in water except the IA, Ca(OH)2,

Sr(OH)2, and Ba(OH)2 hydroxides.

Combustion

Whoosh Bottle Rocket Explosions Dynamite Soap Mixtures Repeating Exploding Flask