Visualizing a Chemical Reaction 2 Na + Cl2 NaCl 2 ___ mole Na 10 10 ___ mole Cl2 5 5 ___ mole NaCl 10 10 ?

Formation of Ammonia

Proportional Relationships 2 1/4 c. flour 1 tsp. baking soda 1 tsp. salt 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. Conversion Factor I have 5 eggs. How many cookies can I make? 2 1/4 cups all-purpose flour 1 tsp baking soda 1 tsp salt 1 cup (2 sticks) butter, softened 3/4 cup granulated sugar 3/4 cup packed brown sugar 1 tsp vanilla extract 2 eggs 2 cups (12 oz. package) chocolate morsels 1 cup chopped nuts (walnuts, pecans or macadamia) Preheat oven to 400oF.  Combine flour, baking soda and salt in bowl. Beat butter, granulated and brown sugars, and vanilla in large bowl until creamy.  Add eggs one at a time until smooth. Gradually add dry ingredients.  When well blended add morsels and nuts.  I prefer to hand stir at this point not to break or melt the chocolate morsels. Drop by tablespoon-fulls onto ungreased baking sheets, keeping about 2" apart.  Bake for 9 to 11 minutes until golden brown.  Cool on baking sheet for a couple of minutes and transfer to wire rack until completely cool, being sure to eat at least one while warm to ensure quality control! http://www.oldetimecooking.com/Images/Recipes/chocchipcookie.jpg Ratio of eggs to cookies 5 eggs 5 dozen 2 eggs = 12.5 dozen cookies 150 cookies 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 A balanced chemical equation gives the identity of the reactants and products and the accurate number of molecules or moles of each that are consumed or produced. Stoichiometry is a collective term for the quantitative relationships between the masses, numbers of moles, and numbers of particles (atoms, molecules, and ions) of the reactants and products in a balanced reaction. A stoichiometric quantity is the amount of product or reactant specified by the coefficients in a balanced chemical equation. 2 Mg + O2  2 MgO Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Stoichiometry Steps Core step in all stoichiometry problems!! 1. Write a balanced equation. 2. Identify known & unknown. 3. Line up conversion factors. Mole ratio - moles  moles Molar mass - moles  grams Molarity - moles  liters soln Molar volume - moles  liters gas Mole ratio - moles  moles Core step in all stoichiometry problems!! 4. Check answer. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Standard Temperature & Pressure Molar Volume at STP 1 mol of a gas=22.4 L at STP Standard Temperature & Pressure 0°C and 1 atm Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Molar Volume at STP MOLES LITERS OF GAS AT STP (22.4 L/mol) MASS IN GRAMS MOLES NUMBER OF PARTICLES Molar Mass (g/mol) 6.02  1023 particles/mol 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 9 mol O2 2 mol KClO3 3 mol O2 = 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 3 1. 2 Sb + 3 Cl2  2 SbCl3 = excess 5 mol 7.5 mol excess x mol How many moles of chlorine gas are required to react with 5 moles of antimony? 3 mol Cl2 x mol Cl2 = 5 mol Sb = 7.5 mol Cl2 2 mol Sb How many moles of SbCl3 are produced from 5 moles of antimony and excess Cl2? 2 mol SbCl3 x mol SbCl3 = 5 mol Sb = 5 mol SbCl3 2 mol Sb How many moles of SbCl3 are produced from 7.5 moles of Cl2 and excess Sb? 2 mol SbCl3 x mol SbCl3 = 7.5 mol Cl2 = 5 mol SbCl3 3 mol Cl2

2. 2 Mg + O2  2 MgO 10 mol x L x mol How many moles of magnesium oxide are produced from the burning of 10 mol of Mg? 2 mol MgO x mol MgO = 10 mol Mg = 10 mol MgO 2 mol Mg How many liters of oxygen are needed to burn 10 mol of Mg? Assume 1 mol O2 = 22.4 L 1 mol O2 22.4 L O2 x L O2 = 10 mol Mg = 5 mol O2 = 112 L O2 2 mol Mg 1 mol O2 1 mol O2 22.4 L O2 x L O2 = 10 mol Mg = 112 L O2 2 mol Mg 1 mol O2

3. CaCl2  Ca + Cl2 8 mol x mol How many moles of calcium metal are produced from the decomposition of 8 mol of calcium chloride? and chlorine gas 1 mol Ca x mol Ca = 8 mol CaCl2 = 8 mol Ca 1 mol CaCl2 How many moles of calcium metal and chlorine gas are produced from the decomposition of 8 mol of calcium chloride? 1 mol Cl2 x mol Cl2 = 8 mol CaCl2 = 8 mol Cl2 1 mol CaCl2

Ions in Aqueous Solution Print Copy of Lab Pb(NO3)2(s) + H2O(l) Pb(NO3)2(aq) Pb2+(aq) + 2 NO31–(aq) Pb2+ NO31– Pb2+ NO31– add water in solution NO31– NO31– dissociation: NaI(s) + H2O(l) NaI(aq) Na1+(aq) + I1–(aq) Na1+ I1– Na1+ I1– Mix them and get… Balance to get overall ionic equation… Cancel spectator ions to get net ionic equation…

Balance to get overall ionic equation… Solubility Chart Mix them and get… Pb(NO3)2(aq) + 2 NaI(aq) PbI2 + NaNO3 PbI2(s) + 2 NO31–(aq) (s) (aq) + 2 Na1+(aq) Pb2+ NO31– Pb2+ I1– solid NO31– I1– Na1+ I1– Na1+ 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)

Mix together Zn(NO3)2(aq) and Ba(OH)2(aq): Solubility Chart Mix together Zn(NO3)2(aq) and Ba(OH)2(aq): Mix them and get… Ba(NO3)2 and Zn(OH)2 (aq) (ppt) Zn(NO3)2(aq) + Ba(OH)2(aq) 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) NO31– OH1– Zn2+ Ba2+ 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)

(NH4)3PO4 + Mg(OH)2  Mg3(PO4)2 3 + 6 NH4OH ? 2 (NH4)3PO4 + Mg(OH)2  Mg3(PO4)2 3 + 6 NH4OH ammonium phosphate magnesium hydroxide magnesium phosphate ammonium hydroxide NH41+ OH1- Now you try… 2 AlCl3 + Li2CO3  Al2(CO3)3 + LiCl 3 6

Al2(SO4)3(aq) + 6 NH4OH(aq)  2 Al(OH)3 + 3 (NH4)2SO4 (ppt) (aq) 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- NH41+ SO42- sulfate + hydroxide  aluminum aluminum ammonium ammonium aluminum hydroxide + ammonium sulfate Al2(SO4)3(aq) + 6 NH4OH(aq)  2 Al(OH)3 + 3 (NH4)2SO4 (ppt) (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 NaCl 2 g sodium + 1 g chlorine = 2 g sodium chloride 2 mol sodium 1 mol chlorine 2 mol sodium chloride (2 mol Na) x (23 g/mol) (1 mol Cl2) x (71 g/mol) (2 mol NaCl) x (58.5 g/mol) 46 g 71 g 117 g 117 g

Classes of Reactions Chemical reactions Precipitation reactions Oxidation-Reduction Reactions Acid-Base Reactions Combustion Reactions

Summary of Classes of Reactions Chemical reactions Precipitation reactions Oxidation-Reduction Reactions Acid-Base Reactions Combustion Reactions Synthesis reactions (Reactants are elements.) Decomposition reactions (Products are elements.)

Summary of Classes of Reactions Chemical reactions Precipitation reactions Oxidation-Reduction Reactions Acid-Base Reactions Combustion Reactions Synthesis reactions Decomposition reactions

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

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

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