Creating a Positive Learning Environment for Everyone Be respectful of your classmates Save conversation for clicker portions of lecture Put cell phones in “airplane” mode Turn off tablets Close laptops

Announcements Exam #2: Tuesday, Oct. 31th, 7:00-8:30pm Review Sessions will be posted soon Old exams are posted on course website Sign up for conflict exam (5-6:30 pm) in 1026 Chem Annex Online HW 5 (Type II) due tomorrow by 7:00pm Lab This Week: Review Questions for Exam 2 (answers due online by 10/27 at 5:00pm) Stoichiometry Workshop on Thursday Must be present in lecture to get credit!

Clicker #1 6 mol H2 reacts with 4 mol O2 Limiting Mol Product Leftover Reactant A) H2 4 mol 2 mol O2 B) H2 6 mol 1 mol O2 C) O2 4 mol 2 mol H2 D) O2 8 mol 4 mol H2 E) Neither 10 mol None

Clicker #2 12 mol H2 reacts with 5 mol O2 Limiting Mol Product Leftover Reactant A) H2 6 mol 1 mol O2 B) H2 12 mol 7 mol O2 C) O2 5 mol 7 mol H2 D) O2 10 mol 2 mol H2 E) Neither 12 mol None

Clicker #3 16.128 g H2 reacts with 96.00 g O2 Limiting Mol Product Leftover Reactant A) H2 4 mol 1 mol O2 B) H2 8 mol 1 mol O2 C) O2 1.5 mol 2 mol H2 D) O2 6 mol 2 mol H2 E) Neither 6 mol None

Example #1 2H2(g) + O2(g)  2H2O(g) To react 10.0 g of hydrogen gas, what volume of oxygen gas would you need at 1.05 atm and 22°C? 2H2(g) + O2(g)  2H2O(g)

Example 1 - Clicker #4 2H2(g) + O2(g)  2H2O(g) To react 10.0 g of hydrogen gas, what volume of oxygen gas would you need at 1.05 atm and 22°C? 2H2(g) + O2(g)  2H2O(g) Next Step? A) Use PV = nRT B) Find limiting reactant C) Use mole ratio between H2 and O2

Example #2 - Clicker #5 Given 3.00 g of Mg, how much 3.00 M HCl do we need (in mL)? Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) _________________________________________________________ Does this problem involve finding a limiting reactant? A) Yes B) No C) No idea

Example #2 Given 3.00 g of Mg, how much 3.00 M HCl do we need (in mL)? Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

Example #3 - Clicker #6 Which case makes the larger balloon (at the same temperature and pressure)? Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) Case #1: 10.0 g Mg with 586 mL of 3.00 M HCl Case #2: 15.0 g Mg with 274 mL of 3.00 M HCl -------------------------------------------------------------------------------------------------------------------------- Does this problem involve finding a limiting reactant? A) Yes B) No C) No idea

Example #3 Which case makes the larger balloon (at the same temperature and pressure)? Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) Case #1: 10.0 g Mg with 586 mL of 3.00 M HCl Case #2: 15.0 g Mg with 274 mL of 3.00 M HCl

Example #4 Consider the reaction: (NH4)2CO3(s)  2NH3(g) + CO2(g) + H2O(g) What total volume of gas is produced, measured at 453oC and 1.04 atm, if 52.0 g of ammonium carbonate is heated?

Example #4 - Clicker #7 Consider the reaction: (NH4)2CO3(s)  2NH3(g) + CO2(g) + H2O(g) What total volume of gas is produced, measured at 453oC and 1.04 atm, if 52.0 g of ammonium carbonate is heated? __________________________________________________ First step? Find volume using PV=nRT Use mole ratio between ammonium and carbon dioxide Convert mass of ammonium carbonate to moles

Example #4 - Clicker #8 Consider the reaction: (NH4)2CO3(s)  2NH3(g) + CO2(g) + H2O(g) What total volume of gas is produced, measured at 453oC and 1.04 atm, if 52.0 g of ammonium carbonate is heated? __________________________________________________ Next step? Find moles of water using mole ratio & moles (NH4)2CO3 Find moles of carbon dioxide using mole ratio & moles (NH4)2CO3 Use PV = nRT to find volume of NH3 produced Use PV = nRT to find volume of ammonium carbonate produced A - C are possible

Example #4 Consider the reaction: (NH4)2CO3(s)  2NH3(g) + CO2(g) + H2O(g) What total volume of gas is produced, measured at 453oC and 1.04 atm, if 52.0 g of ammonium carbonate is heated?