Recommended Reading and Problems Recommended Reading Relevant Problems Chapter , Review (balancing) Review (classifying matter)

Unit Overview Monday 10/5: Net Ionic Equations Tuesday 10/06: Net Ionic Equations Wednesday 10/07: Single Replacement & Redox Reactions Thursday 10/08: Bring Book - Double Replacement Reactions Friday 10/09: Bring Book - Combustion Reaction Review Monday 10/12: Addition Reactions Tuesday 10/13: Quiz & Decomposition Reactions Wednesday 10/14: Lab Thursday 10/15: Lab Friday 10/16: Unit 3 Exam

Monday October 05 Warm-up: Write the balanced equation for Silver Nitrate solution being combined with Sodium Chloride solution to form solid Silver Chloride and Sodium Nitrate solution Learning Objectives LO 3.2 The student can translate an observed chemical change into a balanced chemical equation and justify the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances. LO 3.8 The student is able to identify redox reactions and justify the identification in terms of electron transfer. Unit: AP Style Net Ionic Equations & Reaction Types Today’s Topic: Net Ionic Equations Upcoming: Tuesday: Continue Net Ionic Wednesday: Redox & Single Replacement Thursday: Double Replacement (precipitation reactions) Friday: Combustion Review

Formula Equation (Molecular Equation) Gives the overall reaction stoichiometry but not necessarily the actual forms of the reactants and products in solution. Reactants and products generally shown as compounds. Use solubility rules to determine which compounds are aqueous and which compounds are solids. AgNO 3 (aq) + NaCl(aq) AgCl(s) + NaNO 3 (aq)

Complete Ionic Equation All substances that are strong electrolytes are represented as ions. Ag + (aq) + NO 3 - (aq) + Na + (aq) + Cl - (aq) AgCl(s) + Na + (aq) + NO 3 - (aq)

Net Ionic Equations Includes only those solution components undergoing a change. ◦ Show only components that actually react. Ag + (aq) + Cl - (aq) AgCl(s) Spectator ions are not included (ions that do not participate directly in the reaction). ◦ Na + and NO 3 - are spectator ions.

Tuesday October 06 Warm-up: Write the balanced equation for Silver Nitrate solution being combined with Sodium Chloride solution to form solid Silver Chloride and Sodium Nitrate solution Learning Objectives LO 3.2 The student can translate an observed chemical change into a balanced chemical equation and justify the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances. LO 3.8 The student is able to identify redox reactions and justify the identification in terms of electron transfer. Unit: AP Style Net Ionic Equations & Reaction Types Today’s Topic: Net Ionic Equations Upcoming: Tuesday: Continue Net Ionic Wednesday: Redox & Single Replacement Thursday: Double Replacement (precipitation reactions) Friday: Combustion Review

Check in! Write the correct formula equation, complete ionic equation, and net ionic equation for the reaction between cobalt(II) chloride and sodium hydroxide. Formula Equation: CoCl 2 (aq) + 2NaOH(aq) Co(OH) 2 (s) + 2NaCl(aq) Complete Ionic Equation: Co 2+ (aq) + 2Cl - (aq) + 2Na + (aq) + 2OH - (aq) Co(OH) 2 (s) + 2Na + (aq) + 2Cl - (aq) Net Ionic Equation: Co 2+ (aq) + 2Cl - (aq) Co(OH) 2 (s)

Check in: Solving Stoichiometry Problems for Reactions in Solution 1.Identify the species present in the combined solution, and determine what reaction occurs. 2.Write the balanced net ionic equation for the reaction. 3.Calculate the moles of reactants. 4.Determine which reactant is limiting. 5.Calculate the moles of product(s), as required. 6.Convert to grams or other units, as required.

Problem Solving 10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change).  What Precipitate will form?  What mass of precipitate will form? Where are we going? To find the mass of precipitate formed. How do we get there? What are the ions present in the combined solution? What is the balanced net ionic equation for the reaction? What are the moles of reactants present in the solution? Which reactant is limiting? What moles of precipitate will be formed? What mass of precipitate will be formed?

10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution 1)Write balanced molecular equation to find the precipitate formed 2)Solid is Pb 3 (PO 4 ) 2 The balanced molecular equation is: 2Na 3 PO 4 (aq) + 3Pb(NO 3 ) 2 (aq) → 6NaNO 3 (aq) + Pb 3 (PO 4 ) 2 (s).

10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution mol Na 3 PO 4 present to start and mol Pb(NO 3 ) 2 present to start. Pb(NO 3 ) 2 is the limiting reactant, therefore mol of Pb 3 (PO 4 ) 2 is produced. Since the molar mass of Pb 3 (PO 4 ) 2 is g/mol: 1.1 g of Pb 3 (PO 4 ) 2 will form. Where are we going? ◦ To find the mass of Pb 3 (PO 4 ) 2 formed. How do we get there? ◦ What are the moles of reactants present in the solution? ◦ Which reactant is limiting? ◦ What moles of Pb 3 (PO 4 ) 2 will be formed? ◦ What mass of Pb 3 (PO 4 ) 2 will be formed?

Check in Problem 10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change). What is the concentration of nitrate ions left in solution after the reaction is complete?

Think about the process Where are we going? ◦ To find the concentration of nitrate ions left in solution after the reaction is complete. How do we get there? ◦ What are the moles of nitrate ions present in the combined solution? ◦ What is the total volume of the combined solution?

Check Problem 10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change). What is the concentration of nitrate ions left in solution after the reaction is complete? 0.27 M

Check in Problem 10.0 mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change). What is the concentration of phosphate ions left in solution after the reaction is complete?

Think about the process Where are we going? ◦To find the concentration of phosphate ions left in solution after the reaction is complete. How do we get there? ◦What are the moles of phosphate ions present in the solution at the start of the reaction? ◦How many moles of phosphate ions were used up in the reaction to make the solid Pb 3 (PO 4 ) 2 ? ◦How many moles of phosphate ions are left over after the reaction is complete? ◦What is the total volume of the combined solution?

Check in mL of a 0.30 M sodium phosphate solution reacts with 20.0 mL of a 0.20 M lead(II) nitrate solution (assume no volume change). What is the concentration of phosphate ions left in solution after the reaction is complete? M

Wednesday October 07 Warm-up: Write the net ionic equation for mixing potassium chromate solution with barium nitrate solution. CrO 4 2- (aq) + Ba 2+ (aq)  BaCrO 4 (s) Learning Objectives LO 3.2 The student can translate an observed chemical change into a balanced chemical equation and justify the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances. LO 3.8 The student is able to identify redox reactions and justify the identification in terms of electron transfer. Unit: AP Style Net Ionic Equations & Reaction Types Today’s Topic: Redox Reactions & Single Replacement Reactions Upcoming: Thursday: Double Replacement (precipitation reactions) Friday: Combustion Review

Types of Equations Type of EquationFormat Single ReplacementAB + C  AC + B or AB + D  CB + A Double Replacement (includes precipitation reactions) AB + CD  AD + CB CombustionMost frequently: Hydrocarbon + Oxygen  Carbon Dioxide + Water Addition (also called synthesis)A + B  AB DecompositionAB  A + B Oxidation-Reductionreaction in which one or more electrons are transferred

Balancing Redox Reactions – half reactions occurring in Acidic Solutions Reviewing Terms: Oxidation – reduction (redox) reaction – involves a transfer of electrons from the reducing agent to the oxidizing agent Oxidation – loss of electrons Reduction – gain of electrons Reducing agent – electron donor Oxidizing agent – electron acceptor

Half Reactions The overall reaction is split into two half–reactions, one involving oxidation and one involving reduction. (in ionic form) 8H + + MnO 4 – + 5Fe 2+ Mn Fe H 2 O Reduction: 8H + + MnO 4 – + 5e – Mn H 2 O Oxidation: 5Fe 2+ 5Fe e –

The Half–Reaction Method for Balancing Equations for Oxidation–Reduction Reactions Occurring in Acidic Solution  Electrochemistry 1.Write separate equations for the oxidation and reduction half–reactions. 2.For each half–reaction: A.Balance all the elements except H and O. B.Balance O using H 2 O. C.Balance H using H +. D.Balance the charge using electrons.

Continued…. 3.If necessary, multiply one or both balanced half– reactions by an integer to equalize the number of electrons transferred in the two half–reactions. 4.Add the half–reactions, and cancel identical species. 5.Check that the elements and charges are balanced.

How can we balance this equation? First Steps: ◦ Separate into half-reactions. ◦ Balance elements except H and O. Cr 2 O 7 2- (aq) 2Cr 3+ (aq) SO 3 2- (aq) SO 4 2- (aq)

How many electrons are involved in each reaction? 6e - + Cr 2 O 7 2- (aq) 2Cr 3+ (aq) SO 3 2- (aq) SO 4 2- (aq) + 2e -

How can we balance the oxygen atoms? 6e - + Cr 2 O 7 2- (aq) 2Cr 3+ (aq) +7H 2 O H 2 O + SO 3 2- (aq) SO 4 2- (aq) + 2e -

How can we balance the hydrogen atoms? (remember that this reaction occurs in acidic solution) 14H + + 6e - + Cr 2 O 7 2- (aq) 2Cr 3+ (aq) +7H 2 O H 2 O + SO 3 2- (aq) SO 4 2- (aq) + 2e - + 2H +

Now balance the electrons so that each half reaction has the same amount 14H + + 6e - + Cr 2 O 7 2- (aq) 2Cr 3+ (aq) +7H 2 O 3[H 2 O + SO 3 2- (aq) SO 4 2- (aq) + 2e - +2H + ] Combine and cancel products/reactants for your final balanced equation: Cr 2 O SO H + 2Cr SO H 2 O

Check in Balance the following oxidation–reduction reaction that occurs in acidic solution. Br – (aq) + MnO 4 – (aq) Br 2 (l)+ Mn 2+ (aq) 10Br – (aq) + 16H + (aq) + 2MnO 4 – (aq) 5Br 2 (l)+ 2Mn 2+ (aq) + 8H 2 O(l)

Half-Reactions in Basic Solution 1.Use the half–reaction method as specified for acidic solutions to obtain the final balanced equation as if H + ions were present. 2.To both sides of the equation obtained above, add a number of OH – ions that is equal to the number of H + ions. (We want to eliminate H + by forming H 2 O.) 3.Form H 2 O on the side containing both H + and OH – ions, and eliminate the number of H 2 O molecules that appear on both sides of the equation. 4.Check that elements and charges are balanced.

Balancing half reactions in basic solutions

Thursday October 08 Warm-up: Write the net ionic equation for mixing potassium hydroxide solution with iron nitrate solution. Fe 3+ (aq) + 3OH - (aq)  Fe(OH) 3 (s) Learning Objectives LO 3.2 The student can translate an observed chemical change into a balanced chemical equation and justify the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances. LO 3.8 The student is able to identify redox reactions and justify the identification in terms of electron transfer. Unit: AP Style Net Ionic Equations & Reaction Types Today’s Topic: Double Replacement / Precipitation Reactions Upcoming: Friday: Combustion Review Monday: Synthesis / Addition Reactions Tuesday: Decomposition Reactions Wednesday-Thursday: Lab Friday: Exam

Double Replacement Reactions Using your solubility rules predict what will happen when the following pairs of solutions are mixed (reaction or no reaction): 1) Potassium Nitrate and Barium Chloride 2) Sodium Sulfide and Lead Nitrate 3) Potassium Chromate and Barium Nitrate

Double Replacement Reactions Write the Complete Ionic Equation and Net Ionic Equation for the below: 1) Sodium Sulfide and Lead Nitrate 2) Potassium Chromate and Barium Nitrate

Practice Sheet Work on the net ionic practice sheet – answers are at my desk and you are welcome to check them after you have tried the problem

Friday October 09 What type of reaction does this equation represent? How can you tell? 2Na(s) + Cl 2 (g)  2NaCl(s) Learning Objectives LO 3.2 The student can translate an observed chemical change into a balanced chemical equation and justify the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances. LO 3.8 The student is able to identify redox reactions and justify the identification in terms of electron transfer. Unit: AP Style Net Ionic Equations & Reaction Types Today’s Topic: Combustion Review Upcoming: Monday: Synthesis / Addition Reactions Tuesday: Decomposition Reactions & QUIZ Wednesday-Thursday: Lab Friday: Exam

Combustion Reaction Combustion reactions always involve molecular oxygen O2. Anytime anything burns (in the usual sense), it is a combustion reaction. Combustion reactions are almost always exothermic (i.e., they give off heat). Hydrocarbon + oxygen gas  carbon dioxide + water