Chemical Equations & Reactions - teachnlearnchem.com

Chemical Equations & Reactions - teachnlearnchem.com

Chemical Equations & Reactions http://www.unit5.org/chemistry/Equations.html Lecture Outline Chemical Equations & Reactions Lecture Outline Chemical Equations & Reactions student notes outline textbook questions Lecture Outline Chemical Equations & Reactions textbook questions Keys Keys text http://www.unit5.org/chemistry/Equations.html Chemical Reactions You should be able to Classify reactions by type. Write a balanced molecular equation, complete ionic equation, and a net ionic equation. Balance oxidation-reduction reactions. Predict if a precipitate will form using the solubility rules. Predict products of reactions given the chemical names of the reactants. Organize Your Thoughts Chemical reactions Chemical equations Balancing equations Predicting products from reactants Packard, Jacobs, Marshall, Chemistry Pearson AGS Globe, page 175 Chemical equations

Synthesis Decomposition Single replacement Double replacement Combustion Describing a Chemical Reaction Indications of a Chemical Reaction Evolution of heat, light, and/or sound Production of a gas Formation of a precipitate Color change Signs of Chemical Reactions There are five main signs that indicate a chemical reaction has taken place: release input change in color change in odor production of new gases or vapor input or release of energy difficult to reverse Chemical Equations aluminum oxide Depict the kind of reactants and product products and their relative amounts in a reaction. 4 Al(s) + 3 O2(g) 2 Al2O3(s)

The letters (s), (g), and (l) are the physical states of compounds. The numbers in the front are called stoichiometric coefficients. Chemical Equations 4 Al(s) + 3 O2(g) 2 Al2O3(s) aluminum oxide sandpaper 4 g Al + 3 g O2 yield 2 g Al2O3 This equation means: 4 Al atoms + 3 O2 molecules yield 2 molecules of Al2O3 or 4 Al moles + 3 O2 moles yield 2 moles of Al2O3 4 mol [email protected]/mol 108 g 3 mol [email protected]/mol + 96 g 2 mol [email protected]/mol = 204 g Chemical Equations Because the same atoms are present in a reaction at the beginning (reactants) and at the end (products), the amount of matter in a system does not change. The Law of Conservation of Matter 100% Kotz web Chemical Factory 100%

20% 80% Chemical Equations Because of the principle of the conservation of matter, An equation must be balanced. It must have the same number of atoms of the same kind on both sides. Lavoisier, 1788 Characteristics of Chemical Equations The equation must represent known facts. The equation must contain the correct formulas for the reactants and products. The law of conservation of mass must be satisfied. Chemical Equations Reactants the substances that exist before a chemical change (or reaction) takes place. Products the new substance(s) that are formed during the chemical changes. CHEMICAL EQUATION indicates the reactants and products of a reaction. REACTANTS PRODUCTS Word Equations A WORD EQUATION describes chemical change using the names of the reactants and products. Write the word equation for the reaction of methane gas with oxygen gas to form carbon dioxide and water. methane + oxygen Reactant

CH4 + 2 O2 carbon dioxide + water Product CO2 + 2 H2O Unbalanced and Balanced Equations H Cl Cl H H H H Cl H2 + Cl2 HCl (unbalanced) reactants H Cl 2 2 H H

Cl Cl Cl H2 + Cl2 2 HCl (balanced) reactants products 1 1 Cl H Cl 2 2 products 2 2 Visualizing a Chemical Reaction 2 Na 10 mole Na ___ + Cl 2 5 mole Cl2 ___ 2 NaCl 10 ? mole NaCl ___

Visualizing a Chemical Reaction 2 Na + Cl 2 2 NaCl Meaning of Chemical Formula Chemical Symbol H2O Meaning One molecule of water: Composition Two H atoms and one O atom 2 H2O Two molecules of water: Four H atoms and two O atoms H2O2 One molecule of hydrogen peroxide: Two H atoms and two O atoms Balancing Chemical Equations Balanced Equation one in which the number of atoms of each element as a reactant is equal to the number of atoms of that element as a product What is the relationship between conservation of mass and the fact that a balanced equation will always have the same number of atoms of each element on both sides of an equation?

Determine whether the following equation is balanced. 2 Na + H2O 2 NaOH + H2 2 Na + 2 H2O 2 NaOH + H2 Balancing Chemical Equations Write a word equation for the reaction. Write the correct formulas for all reactants and products. Determine the coefficients that make the equation balance. Balancing Chemical Equations Other examples NO(g) + O2(g) NO2(g) is it balanced? Is this balanced? NO(g) + O(g) NO2(g) Is this OK? Is this balanced? NO(g) + O2(g) NO2(g) Is this OK? Balancing Chemical Equations An important point to remember 2 NO(g) + O2(g) 2NO2(g) The 2 to the left of NO(g) and NO2(g) refers to the number of molecules present in the balanced equation. It is a multiplier for every atom in the molecule. The subscript 2 in O2 (g) and NO2(g) refers to the number of atoms of this type that are present in each molecules (or ionic compound). Guidelines for Balancing Chemical Equations ? 1) polyatomic ions first 2) even / odd (make all even) 3) 2 H-OH vs. H2O Mg(OH)2 4) single elements last Example: need 13 oxygen atoms Multiply by 13 O2 = 13 2

3X + 13 2 O2 2Y + Z 13 3X + 2 2 O2 2Y + Z 4Y + 2Z 6X + 13 O2 2 (NH4)3PO4 +3 Mg(OH)2 Mg3(PO4)2 ammonium phosphate 6 NH? 4OH + ammonium hydroxide magnesium phosphate magnesium hydroxide NH41+ Now you try 2 AlCl3 + 3 Li2CO3

Al2(CO3)3 + 6LiCl OH1- Write a balanced equation for the reaction between chlorine and sodium bromide to produce bromine and sodium chloride. 1) Write a word equation for the reaction. chlorine + sodium bromide bromine + sodium chloride 2) Write the correct formulas for all reactants and products. Cl2 + NaBr Br2 + NaCl 3) Determine the coefficients that make the equation balance. Cl2 + 2 NaBr Br2 + 2 NaCl

Write the balanced equation for the reaction between aluminum sulfate and calcium chloride to form a white precipitate of calcium sulfate. 1) Write a word equation for the reaction. ? ? aluminum sulfate + calcium chloride calcium sulfate + aluminum chloride 2) Write the correct formulas for all reactants and products. Al2(SO4)3 + CaCl2 CaSO4 + AlCl3 3) Determine the coefficients that make the equation balance. Al2(SO4)3 + 3 CaCl2 3 CaSO4 + 2 AlCl3 CH4 + 2 O2 CO2 + 2 H2O Reactants

1 C atom 4 H atoms 4 O atoms Products 1 C atom 4 H atoms 4 O atoms Reactants Products + C(s) + carbon O2(g) CO2(g) oxygen carbon dioxide Reactants 1 carbon atom 2 oxygen atoms Product 1 carbon atom 2 oxygen atoms catalyst speeds up reaction + 2 H2(g) + hydrogen Reactants 2 hydrogen atoms 4 2 oxygen atoms

Pt O2(g) Pt oxygen 2 H2O (l) water Product 2 hydrogen atoms 4 1 oxygen atoms 2 Unbalanced Showing Phases in Chemical Equations H2O(s) H2O(l) H2O(g) Solid Phase the substance is relatively rigid and has a definite volume and shape. NaCl(s) Liquid Phase the substance has a definite volume, but is able to change shape by flowing. H2O(l) Gaseous Phase the substance has no definite volume or shape, and it shows little response to gravity. Cl2(g) Additional Symbols Used in Chemical Equations Yields; indicates result of reaction Used to indicate a reversible reaction (s) A reactant or product in the solid state; also used to indicate a precipitate Alternative to (s), but used only to indicate a precipitate

(l) (aq) (g) A reactant or product in the liquid state A reactant or product in an aqueous solution (dissolved in water) A reactant or product in the gaseous state Additional Symbols Used in Chemical Equations Alternative to (g), but used only to indicate a gaseous product D 2 atm pressure Reactants are heated Pressure at which reaction is carried out, in this case 2 atm Pressure at which reaction is carried out exceeds normal atmospheric pressure 0 oC Temperature at which reaction is carried out, in this case 0 oC MnO2 Formula of catalyst, in this case manganese (IV) oxide, used to alter the rate of the reaction Solubility Ionic Equations Cover the answers, work the problem, then check the answer. 1. Dissolve ammonium nitrate: NH4NO3 (s) ---> NH4+1 (aq) + NO3-1 (aq) 2. Precipitate cupric hydroxide: Cu+2 (aq) + 2OH-1 (aq) ---> Cu(OH)2 (s) 3. Dissolve chromium thiocyanate: 4. Precipitate lead arsenate:

Cr(SCN)3 (s) ---> Cr+3 (aq) + 3SCN-1 (aq) 3Pb+2 (aq) + 2AsO4-3 (aq) ---> Pb3(AsO4)2 (s) 5. Dissolve silicon permanganate: Si(MnO4)4 (s) ---> Si+4 (aq) + 4MnO4-1 (aq) 6. Precipitate zinc phosphate: 3Zn+2 (aq) + 2PO4-3 (aq) ---> Zn3(PO4)2 (s) Types of Chemical Reactions Synthesis (Combination) reaction A + B AB AB A + B Decomposition reaction A + BC AC + B Single-replacement reaction A element B Double-replacement reaction Polymerization use activity series to predict A driving forcewater, gas, or precipitate B element compound compound

compound HX + BOH BX + HOH acid Combustion reaction (of a hydrocarbon) compound AB + CD AD + CB compound Neutralization reaction compound base salt water CH + O2 CO2 + H2O Polymer = monomer + monomer + Types of Chemical Reactions Synthesis (Combination) reaction Decomposition reaction AB A + B Single-replacement reaction A + BC AC + B Double-replacement reaction AB + CD AD + CB A B A + B AB

Neutralization reaction Combustion reaction (of a hydrocarbon) Polymerization use activity series to predict A driving forcewater, gas, or precipitate B HX + BOH BX + HOH CH + O2 CO2 + H2O Polymer = monomer + monomer + Chemical Equations Chemical Equations N2 (g) 3 H2 (g) + 2 NH3 (g) + Microscopic recipe Macroscopic recipe 1 molecule N2 + 1 mol N2 + Experimental Conditions 3 molecules H2 3 mol H2

Reactants 2 molecules NH3 2 mol NH3 Products Before reaction 1 mol N2 + 3 mol H2 2 mol NH3 2 molecules N2 3 molecules H2 0 molecules NH3 1 molecules N2 0 molecules H2 2 molecules NH3 After reaction Nitrogen is in excess or hydrogen is limiting reagent. Synthesis Reaction Direct combination reaction (Synthesis) 2 Na + Na Cl2 Cl Cl

2 NaCl Na General form: A + B element or element or compound compound AB compound Synthesis Reaction Direct combination reaction (Synthesis) 2 Na + Cl2 Na 2 NaCl Cl Na+ Cl - Cl Cl - Na+ Na General form: A

+ B element or element or compound compound AB compound Formation of a solid: AgCl AgNO3(aq) + KCl(aq) KNO3 (aq) + AgCl(s) lead (II) chloride + potassium iodide K1+ Pb2+ Cl1PbCl2 + I1- KI Copyright 2007 Pearson Benjamin Cummings. All rights reserved. potassium chloride + lead (II) iodide Pb2+ Cl1KCl (aq) K1+ + I1- PbI2 (ppt) lead (II) chloride + potassium iodide K1+

Pb2+ Cl1PbCl2 + I1- KI Copyright 2007 Pearson Benjamin Cummings. All rights reserved. potassium chloride + lead (II) iodide Pb2+ Cl1KCl (aq) K1+ + I1- PbI2 (ppt) lead(II) chloride + potassium iodide Pb2+ I1- K1+ Cl1- Pb Cl(aq) 2 + Pb2+ I 2 K (aq) + 2 K1+(aq) + 2 I1-(aq) Pb2+(aq) + 2 Cl1-(aq) potassium chloride + lead(II) iodide

Pb2+ Cl1- Cl1- KCl(aq) 2 K1+(aq) + 2 Cl1-(aq) I Cl + Pb2+(aq) + 2 I1-(aq) Cl1- I1- I1Cl1- K1+ I1- REACTANTS Copyright 2007 Pearson Benjamin Cummings. All rights reserved. Pb2+ I1- PbI2 (ppt) K1+ I 1- 1- + Pb2+ K1+

1- K1+ K1+ I1- PRODUCTS Double Replacement Reaction aqueous barium nitrate reacts with sulfuric acid [H 2SO4(aq)] to yield a barium sulfate precipitate and nitric acid [HNO 3(aq)] barium nitrate Ba 2+ NO + sulfuric acid H 1+ 13 Ba(NO3)2(aq) + Ba(NO3)2(aq) SO4 2- H2SO4(aq) + H2SO4(aq) Ba2+(aq) + 2 NO31-(aq) + 2 H1+(aq) + SO42-(aq) Ba2+ NO31-

H1+ barium sulfate Ba 2+ SO4 BaSO4 BaSO4 (ppt) + Ba2+(aq) + SO42-(aq) nitric acid + 2 HNO3 H1+ + 2 H1+(aq) + 2 NO31-(aq) NO31- H1+ SO42- H1+ NO31- Ba2+ SO42REACTANTS NO31- 2 HNO3(aq) Ba2+ SO42NO31-

+ 2- PRODUCTS H1+ aqueous barium nitrate reacts with sulfuric acid [H 2SO4(aq)] to yield a barium sulfate precipitate and nitric acid [HNO 3(aq)] barium nitrate + Ba(NO3)2(aq) sulfuric acid + H2SO4(aq) Ba2+(aq) + 2 NO31-(aq) + 2 H1+(aq) + SO42-(aq) 2+ 1- 1+ barium sulfate BaSO4 (ppt) nitric acid + + Ba2+(aq) + SO42-(aq) 2 HNO3(aq) + 2 H1+(aq) + 2 NO31-(aq)

1- 1+ 21- 1+ REACTANTS 12+ 1+ 2- PRODUCTS Double Replacement Reaction aqueous calcium nitrate reacts with sulfuric acid [H2SO4(aq)] to yield a calcium sulfate precipitate and nitric acid [HNO 3(aq)] calcium nitrate Ca 2+ NO3 + sulfuric acid H 1+ 1- Ca(NO3)2(aq) + Ca(NO3)2(aq) SO4 2- H2SO4(aq)

+ H2SO4(aq) Ca2+(aq) + 2 NO31-(aq) + 2 H1+(aq) + SO42-(aq) Ca2+ NO31- H1+ calcium sulfate Ca 2+ SO4 CaSO4 CaSO4 (ppt) + Ca2+(aq) + SO42-(aq) nitric acid + 2 HNO3 H1+ + 2 H1+(aq) + 2 NO31-(aq) NO31- H1+ SO42- H1+ NO31-

Ca2+ SO42REACTANTS NO31- 2 HNO3(aq) Ca2+ SO42NO31- + 2- PRODUCTS H1+ aqueous calcium nitrate reacts with sulfuric acid [H2SO4(aq)] to yield a calcium sulfate precipitate and nitric acid [HNO 3(aq)] calcium nitrate + Ca(NO3)2(aq) sulfuric acid + H2SO4(aq) Ca2+(aq) + 2 NO31-(aq) + 2 H1+(aq) + SO42-(aq) 2+ 1- 1+ barium sulfate CaSO4 (ppt) nitric acid

+ + Ca2+(aq) + SO42-(aq) 2 HNO3(aq) + 2 H1+(aq) + 2 NO31-(aq) 1- 1+ 21- 1+ REACTANTS 12+ 1+ 2- PRODUCTS Double Replacement Reaction aqueous aluminum phosphate reacts with sodium hydroxide to yield a aluminum hydroxide precipitate and sodium phosphate aluminum phosphate + sodium hydroxide Al3+ Na1+ PO43- OH1- aluminum hydroxide + sodium phosphate Al3+ Na1+ OH1-

AlPO4 (aq) + 3 NaOH (aq) Al(OH)3 + AlPO4(aq) + 3 NaOH(aq) Al(OH)3(ppt) + Al3+(aq) + PO43-(aq) + 3 Na1+(aq) + 3 OH1-(aq) OH1- Al3+ Na1+ Al3+ PO4 OH Na1+ OH1- REACTANTS Na3PO4(aq)

Na1+ OH1OH1- 1- 3- Na3PO4 Al3+(aq) + 3 OH1-(aq) + 3 Na1+(aq) + PO43-(aq) Na1+ OH1- PO43- Na1+ 1OH PO43OH1- Al3+ OH1PRODUCTS Na1+ Double Replacement Reaction aqueous aluminum phosphate reacts with sodium hydroxide to yield a aluminum hydroxide precipitate and sodium phosphate aluminum phosphate + sodium hydroxide Al3+ Na1+ PO43- OH1- AlPO4 (aq) + 3 NaOH (aq) AlPO4(aq) +

3 NaOH(aq) Al3+(aq) + PO43-(aq) + 3 Na1+(aq) + 3 OH1-(aq) 3+ 1- 1+ aluminum hydroxide + sodium phosphate Al3+ Al(OH)3 Al(OH)3(ppt) 1+ 1- REACTANTS + + PO43- Na3PO4 Na3PO4(aq) 1+ 3+ 11- 3- Na1+ Al3+(aq) + 3 OH1-(aq) + 3 Na1+(aq) + PO43-(aq) 1+

1- OH1- 1- 1+ 11- 3+ 1PRODUCTS Decomposition Reaction Decomposition reaction 2 H 2O 2 H2 + O2 H O H + H O H General form: AB compound A + B two or more elements or compounds Single and Double Replacement

Reactions Single-replacement reaction Mg + CuSO4 General form: A + BC MgSO4 AC + + Cu B Double-replacement reaction CaCO3 + General form: AB + 2 HCl CaCl2 +

H2CO3 CD AD + CB Printable Printable Version Version of of Activity Activity Series Series Activity Series Element Reactivity Ca Foiled again Aluminum loses to Calcium Li Rb K Ba Ca Na Mg Al Mn Zn Cr Fe Ni Sn

Pb H2 Cu Hg Ag Pt Au Halogen Reactivity F2 Cl2 Br2 I2 acetate bromide carbonate chloride chromate hydroxide iodide nitrate phosphate sulfate sulfide TABLE OF SOLUBILITIES IN WATER aluminum ss s n

s n i s s i s d ammonium s s s s s s s s s s s barium s

s i s i s s s i i d calcium s s i s s ss s s i ss d copper (II)

s s i s i i n s i s i iron (II) s s i s n i s s i s

i iron (III) s s n s i i n s i ss d lead s ss i ss i i ss s i

i i magnesium s s i s s i s s i s d mercury (I) ss i i i ss n i

s i ss i mercury (II) s ss i s ss i i s i d i potassium s s s s s s

s s s s s silver ss i i i ss n i s i ss i sodium s s s s

s s s s s s s zinc s s i s s i s s i s i Legend SOLID i = insoluble SOLIDsoluble ss = slightly AQUEOUS s = soluble

d = decomposes n = not isolated acetate bromide carbonate chloride chromate hydroxide iodide nitrate phosphate sulfate sulfide TABLE OF SOLUBILITIES IN WATER aluminum s aq n s n s aq aq

s aq d ammonium aq aq aq aq aq aq aq aq aq aq aq barium aq aq s aq s aq aq

aq s s d calcium aq aq s aq aq ss aq aq s s d copper (II) aq aq s aq s

s n aq s aq s iron (II) aq aq s aq n s s aq s aq s iron (III) aq aq n aq

s s n aq s s d lead aq s s ss s s s aq s s s magnesium aq aq

s aq aq s aq aq s aq d mercury (I) s s s s s n s aq s s si Legend mercury (II)

aq s s aq s s s aq s d si potassium aq aq aq aq aq aq aq aq aq aq

aq s = solid aq = aqueous d = decomposes n = not isolated silver s s s s s n s s s s s sodium aq aq aq aq aq aq

aq aq aq aq aq zinc aq aq s aq aq s aq aq s aq s acetate bromide carbonate chloride chromate hydroxide

iodide nitrate phosphate sulfate sulfide TABLE OF SOLUBILITIES IN WATER aluminum ss s n s n i s s i s d ammonium s s s

s s s s s s s s barium s s i s i s s s i i d calcium s s

i s s ss s s i ss d copper (II) s s i s i i n s i s i iron (II)

s s i s n i s s i s i iron (III) s s n s i i n s i ss d

lead s ss i ss i i ss s i i i magnesium s s i s s i s s i

s d mercury (I) ss i i i ss n i s i ss i Legend mercury (II) s ss i s ss i i

s i d i potassium s s s s s s s s s s s s = solid aq = aqueous d = decomposes n = not isolated silver ss i i

i ss n i s i ss i sodium s s s s s s s s s s s zinc s

s i s s i s s i s i Solubility Rules 1. Most nitrates are soluble. 2. Most salts containing Group I ion and ammonium ion, NH4+, are soluble. 3. Most chloride, bromide, and iodide salts are soluble, except Ag+, Pb2+ and Hg22+. 4. Most sulfate salts are soluble, except BaSO4, PbSO4, Hg2SO4, and CaSO4. 5. Most hydroxides except Group 1 and Ba(OH)2, Sr(OH)2, and Ca(OH)2 are only slightly soluble. 6.

Most sulfides, carbonates, chromates, and phosphates are only slightly soluble. Ohn-Sabatello, Morlan, Knoespel, Fast Track to a 5 Preparing for the AP Chemistry Examination 2006, page 91 Potassium reacts with Water POW! Double Replacement Reaction K2CO3 (aq) Potassium carbonate + BaCl2 (aq) Barium chloride 2 KCl (aq) Potassium chloride + BaCO3 (s) Barium carbonate Synthesis Reactions Photosynthesis 6 CO2 + 6 H2O C6H12O6 + Formation of water 2 H2 + O2 2 H 2O Formation of salt 2 Na + Cl2 2 NaCl General Form A + B

C 6 O2 Decomposition Reactions Hydrogen Peroxide 2 H2O2 2 H 2O + O2 Electrolysis of water 2 H2O electricity 2 H2 + O2 Nitrogen triiodide 2 NI3 N2 + 3 I2 General Form AB A + B Predict if these reactions will occur 3 Mg + 2 AlCl3 2 Al + 3 MgCl2 Can magnesium replace aluminum? YES, magnesium is more reactive than aluminum.

Activity Series Al + MgCl2 No reaction Can aluminum replace magnesium? NO, aluminum is less reactive than magnesium. Activity Series MgCl2 + Al Therefore, no reaction will occur. No reaction Order of reactants DOES NOT determine how they react. The question we must ask is can the single element replace its counterpart? metal replaces metal or nonmetal replaces nonmetal. Single-Replacement Reactions Activity Series Magic blue-earth Fe + CuCl2 Can Fe replace Cu? FeCl2 + Cu Yes

Zinc in nitric acid Zn + 2 HNO3 Can Zn replace H? Zn(NO3)2 + H2 Yes NO REACTION MgCl2 + Can Br replace Cl? Br2 MgBr2 + No General Form A + BC AC + B Cl2 Li Rb K Ba Ca Na Mg

Al Mn Zn Cr Fe Ni Sn Pb H2 Cu Hg Ag Pt Au F2 Cl2 Br2 I2 How would you prepare potassium nitrate (using a double replacement reaction)? K KOH HNO H NO OH + +_________ _________ 3 3 Ca(NO3)2 2 KOH + Ca(NO3)2 formation of water is a driving force. KNO33 ++ _________ KNO HH 2O 2O Both potassium nitrate and calcium chloride are soluble (no driving force no reaction!) 2 KNO3 + Ca(OH)2

Combine a potassium hydroxide solution with nitric acid to yield soluble potassium nitrate. KOH(aq) + HNO3(aq) KNO3(aq) + H?2O The water could then be removed by distillation to recover solid potassium nitrate. Predict if a reaction will occur when you combine aqueous solutions of iron (II) chloride with aqueous sodium carbonate solution. If the reaction does occur, write a Balanced balanced chemical equation showing it. (be sure to include phase notation) iron (II) chloride + sodium carbonate Fe2+ Cl1- Na1+ CO32- Fe Cl2 Na2CO3 sodium chloride + iron (II) carbonate Na1+ CO32- Fe2+ Cl1- FeCO3 (ppt) NaCl(aq) Using a SOLUBILITY TABLE: sodium chloride is soluble iron (II) carbonate is insoluble FeCl2 (aq) + Na2CO3 (aq)

Complete Ionic Equation Fe2+(aq) + 2Cl1-(aq) + 2Na1+(aq) + CO32-(aq) 2 NaCl (aq) + FeCO3 (ppt) 2Na1+(aq) + 2Cl1-(aq) + FeCO3(s) Visualizing a Chemical Reaction 2 Na 10 mole Na ___ + Cl 2 5 mole Cl2 ___ 2 NaCl 10 ? mole NaCl ___ Formation of Ammonia N2 (g) 3 H2 (g) + 2 NH3 (g) + 2 atoms N +

6 atoms H 2 atoms N and 6 atoms H 1 molecule N2 + 3 molecules H2 2 molecules NH3 10 molecule N2 + 30 molecules H2 20 molecules NH3 1x 6.02 x 1023 molecules N2 + 1 mol N2 + 3 mol H2 2 mol NH3 28 g N2 + 3 x 2 g H2 2 x 17 g NH3 3x

6.02 x 1023 molecules H2 34 g reactants Assume STP 22.4 L 22.4 L N2 + 22.4 L 22.4 L 67.2 L H2 22.4 L 2x 6.02 x 1023 molecules NH3 34 g products 22.4 L 22.4 L 44.8 L NH3 Proportional Relationships 2 1/4 c. flour 1 tsp. baking soda 1 tsp. salt Conversion

Factor 1 c. butter 3/4 c. sugar 3/4 c. brown sugar 1 tsp vanilla extract 2 eggs 2 c. chocolate chips Makes 5 dozen cookies. I have 5 eggs. How many cookies can I make? 5 eggs 5 dozen 2 eggs Ratio of eggs to cookies 150 dozen cookiescookies = 12.5 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Proportional Relationships Stoichiometry mass relationships between substances in a chemical reaction based on the mole ratio Mole Ratio indicated by coefficients in a balanced equation 2 Mg + O2 2 MgO Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Stoichiometry Steps 1. Write a balanced equation. 2. Identify known & unknown. 3. Line up conversion factors.

Mole ratio Molarratio mass Mole - Molarity Molar volume - moles moles moles grams moles moles moles liters soln moles liters gas Core step in all stoichiometry problems!! 4. Check answer. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Molar Volume at STP 1 mol of a gas=22.4 L at STP Standard Temperature & Pressure 0C and 1 atm Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Molar Volume at STP LITERS OF GAS AT STP Molar Volume (22.4 L/mol) MASS IN GRAMS Molar Mass (g/mol) 6.02 1023 MOLES particles/mol

NUMBER OF PARTICLES Molarity (mol/L) LITERS OF SOLUTION Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Stoichiometry Problems How many moles of KClO3 must decompose in order to produce 9 moles of oxygen gas? 2KClO3 2KCl + 3O2 ? mol 9 mol O2 2 mol KClO3 3 mol O2 9 mol = 6 mol KClO3 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem 1. 2 Sb + 3 Cl2 2 SbCl3 2. 2 Mg + O2 2 MgO 3. CaCl2 Ca + Cl2 4. 2 NaClO3 2 NaCl + 3 O2 5. Fe + 2 HCl FeCl2 + H2 6. CuO + H2 Cu + H2O 7. 2 Al + 3 H2SO4 Al2(SO4)3 + 3 H2 2 5 mol 1. 2 Sb + 3 Cl2 2 SbCl3 excess 5 mol

7.5 excess x mol mol = 3 x mol 2 x = 15 x = 7. 5 mol x mol How many moles of chlorine gas are required to react with 5 moles of antimony? x mol Cl2 = 5 mol Sb 3 mol Cl2 2 mol Sb = 7.5 mol Cl2 How many moles of SbCl3 are produced from 5 moles of antimony and excess Cl2? x mol SbCl3 = 5 mol Sb 2 mol SbCl3 2 mol Sb = 5 mol SbCl3 How many moles of SbCl3 are produced from 7.5 moles of Cl2 and excess Sb? x mol SbCl3 = 7.5 mol Cl2 2 mol SbCl3 3 mol Cl2 = 5 mol SbCl3 2. 2 Mg + O2 2 MgO 10 mol xL

x mol How many moles of magnesium oxide are produced from the burning of 10 mol of Mg? x mol MgO = 10 mol Mg 2 mol MgO 2 mol Mg = 10 mol MgO How many liters of oxygen are needed to burn 10 mol of Mg? Assume 1 mol O2 = 22.4 L x L O2 = 10 mol Mg x L O2 = 10 mol Mg 1 mol O2 2 mol Mg = 5 mol O2 1 mol O2 22.4 L O2 2 mol Mg 1 mol O2 22.4 L O2 1 mol O2 = 112 L O2 = 112 L O2 calcium chloride calcium 3. CaCl2 Ca + Cl2 8 mol chlorine

+ x mol How many moles of calcium metal and chlorine gas are produced from the decomposition of 8 mol of calcium chloride? x mol Ca = 8 mol CaCl2 1 mol Ca 1 mol CaCl2 = 8 mol Ca How many moles of calcium metal and chlorine gas are produced from the decomposition of 8 mol of calcium chloride? x mol Cl2 = 8 mol CaCl2 1 mol Cl2 1 mol CaCl2 = 8 mol Cl2 Ions in Aqueous Solution Pb(NO3)2(s) + H2O(l) Print Print Copy Copy ofofLab Lab Pb(NO3)2(aq) Pb2+(aq) + 2 NO31(aq) Pb2+ NO31 NO31 dissociation: NaI(s) + H2O(l) Na1+

I1 add water NO31 Pb2+ NO31 NaI(aq) Na1+(aq) + I1(aq) Na1+ I1 Mix them and get Balance to get overall ionic equation Cancel spectator ions to get net ionic equation in solution Solubility Chart Mix them and get Pb(NO3)2(aq) + 2 NaI(aq) Pb2+ Na1+ (aq) + 2 Na1+(aq) PbI22(s) (s) ++ 2NaNO NO313 (aq) I1 NO31 Pb2+ NO31 I1

Na1+ solid I1 NO31 in solution Na1+ I1 Na1+ NO31 Balance to get overall ionic equation Pb2+(aq) + 2 NO31(aq) + 2 Na1+(aq) + 2 I1(aq) PbI2(s) + 2 NO31(aq) + 2 Na1+(aq) Cancel spectator ions to get net ionic equation Pb2+(aq) + 2 I1(aq) PbI2(s) Solubility Chart Mix together Zn(NO3)2(aq) and Ba(OH)2(aq): Mix them and get Ba(NO3)2 (aq) and Zn(NO3)2(aq) + Ba(OH)2(aq) Zn(OH)2 (ppt) Zn(OH)2(s) + 2 NO31(aq) + Ba2+(aq) Zn(NO3)2(aq) Ba(OH)2(aq) Zn2+(aq) + 2 NO31(aq)

Ba2+(aq) + 2 OH1(aq) OH1 NO31 Ba2+ Zn2+ NO31 OH1 Balance to get overall ionic equation Zn2+(aq) + 2 NO31(aq) + Ba2+(aq) + 2OH1(aq) Zn(OH)2(s) + 2 NO31(aq) + Ba2+(aq) Cancel spectator ions to get net ionic equation Zn2+(aq) + 2 OH1(aq) Zn(OH)2(s) 2 (NH4)3PO4 +3 Mg(OH)2 Mg3(PO4)2 ammonium phosphate 6 NH? 4OH + ammonium hydroxide magnesium phosphate magnesium hydroxide NH41+ Now you try 2 AlCl3 + 3 Li2CO3

Al2(CO3)3 + 6LiCl OH1- Identify the spectator ions and write a net ionic equation when an aqueous solution of aluminum sulfate is mixed with aqueous ammonium hydroxide. Al3+ SO42- NH41+ OH1- Al3+ OH1- aluminum sulfate + ammonium hydroxide aluminum hydroxide + NH41+ SO42- ammonium sulfate Al2(SO4)3(aq) + 6 NH4OH(aq) 2 Al(OH)3 (ppt) + 3 (NH4)2SO4 (aq) 2 Al3+(aq) + 3 SO42-(aq) + 6 NH41+(aq) + 6 OH1-(aq) 2 Al(OH)3(ppt) + 6 NH41+(aq) + 3 SO42-(aq) spectator ions 2 Al3+(aq) + 6 OH1-(aq) 2 Al(OH)3(ppt) Net Ionic Equation Meaning of Coefficients 2 atoms Na 1 molecule Cl2 2 molecules NaCl

2 Na + Cl2 2 g sodium + 1 g chlorine 2 mol sodium (2 mol Na) x (23 g/mol) 2 NaCl = 1 mol chlorine (1 mol Cl2) x (71 g/mol) 46 g 71 g 117 g 2 g sodium chloride 2 mol sodium chloride (2 mol NaCl) x (58.5 g/mol) 117 g Classes of Reactions Chemical reactions Precipitation reactions Oxidation-Reduction Reactions Combustion Reactions Acid-Base Reactions Summary of Classes of Reactions Chemical reactions Precipitation reactions Oxidation-Reduction Reactions

Combustion Reactions Synthesis reactions (Reactants are elements.) Acid-Base Reactions Decomposition reactions (Products are elements.) Summary of Classes of Reactions Chemical reactions Precipitation reactions Oxidation-Reduction Reactions Combustion Reactions Synthesis reactions Acid-Base Reactions Decomposition reactions IONIC BONDING: Formation of Magnesium Chloride Cl Mg Cl Mg2+

Cl Loses 2e- Each gains 1eMg2+ Cl One magnesium ion Cl1[(2+) MgCl2 Two chloride ions 2 (1-) = 0] magnesium chloride IONIC BONDING: Formation of Magnesium Chloride Cl Mg2+ Cl Mg2+ Cl Loses 2e- Each gains 1eMg2+ Cl One magnesium ion Cl1[(2+) MgCl2 Two chloride ions 2 (1-) = 0]

magnesium chloride Resources - Chemical Equations and Reactions Worksheet - vocabulary Worksheet Balancing Chemical Equations Worksheet Chemical Word Equations Worksheet Quantitative Relationships in Chem. Eqns. Worksheet Chemical Equations (paragraph) Worksheet Real Life Chemistry Worksheet Balancing Equations (visual) Worksheet Lab Ions in Solution Textbook - questions Outline (general)

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