Chemistry 202 Dr. Don DeCoste 3014 Chemistry Annex decoste@illinois.edu 11am-12pm Mondays and Wednesdays (after lecture) 10-11 am Tuesdays and 1-2 pm Thursdays By appointment; open door policy

Lon-Capa 1st HW assignment due Friday, 9/7, 10 pm. It is open now. 1st Quiz due Sunday, 9/9 by 10 pm. It will open Friday, 9/7 at 5 pm.

For Today OWL Textbook Homework Videos Introductory Material Chapter 3: 37, 44, 47, 59, 61, 94, 98   Videos Introductory Material Chapter 3: Stoichiometry Stoichiometry I: Mass to Mass Conversions Stoichiometry II: Limiting Reactants

For Friday OWL Textbook Homework Videos Chapter 3: Stoichiometry   Videos Chapter 3: Stoichiometry Problem Solving in Stoichiometry I: The Set-Up Problem Solving in Stoichiometry II: Method 1 Problem Solving in Stoichiometry III: Method 2 Problem Solving in Stoichiometry IV: Method 3

Clicker Question Which best describes your current status? a) Freshman (1st year) b) Sophomore c) Junior d) Senior e) 5th-year senior

Clicker Question Which best describes your major? a) Chemistry b) Chemical Engineering c) Biology or Life Science (MCB, IB, Biochemistry) d) Engineering (not Chemical) e) Other

Problem Solving: A Journey Where Are We Going?: What are we trying to solve? What does this mean? Where Have We Been?: What do we know? What is given in the problem, and what is our knowledge base? How Do We Get There?: How do we connect what we know to what we are trying to solve? Diagrams and more questions can be useful.

Clicker Question A metal ion has 23 electrons in an ionic compound that is about 30% oxygen by mass. Which metal is in the oxide? a) Vanadium b) Chromium c) Manganese d) Iron e) I am not sure how to do this.  

Make Sure You Understand This… Determine the percent mass of oxygen in each of the following substances H2O (water) (88.81%) H2O2 (hydrogen peroxide) (94.07%)