Chemistry Learning Center 230 Davenport Hall Chemistry TAs available from 9 am – 5pm Mondays – Fridays. Chemistry 202 TAs in the CLC: Mondays: 11am-1pm, 3pm-5pm Wednesdays: 3pm-5pm Thursdays: 3pm-5pm

Lon-Capa 1st HW assignment due Friday, 9/2, 5 pm. It is open now. 1st Quiz due Sunday, 9/4 by 10 pm. It will open Wednesday, 8/31 at 5 pm.

At This Point… Finished Chapter 3 (reading and text homework). Continue reading Chapter 4 (focus on molarity and precipitation stoichiometry) and start doing the Chapter 4 homework.

For Wednesday Continue working on Lon-Capa. Finish Chapter 4. See me or email me if there are any questions or concerns. Watch Chapter 4 video on Precipitation Stoichiometry.

Clicker Question Substance AB2 is 42.86% A by mass. What is the percent B by mass for the substance A2B? A) 14.28% B) 25.00% C) 28.57% D) 57.14% E) 78.57%

Clicker Question Consider the balanced chemical equation: 4A + 3B → 2C + D When equal masses of A and B are reacted, which is limiting? A) If the MMA > MMB, then A must be limiting. B) If the MMA < MMB, then A must be limiting. C) If the MMA > MMB, then B must be limiting. D) If the MMA < MMB, then B must be limiting E) None of the above.

Problems to Know… You dissolve 10.0 g of NaCl in 150.0 mL of solution. Determine the concentration in molarity. [1.14M NaCl] Describe how to make 250.0 mL of 0.1000M NaOH from a stock solution of 8.000M NaOH. [Take 3.125 mL of 8.00M NaOH and add enough water to make 250.0 mL of solution.] SEE SECTION 4.3!!

Formulas for Ionic Compounds are Empirical Formulas

NaCl Dissociates into Ions

p129

Solubility Rules

p130

Precipitation Reactions Know how to use the solubility rules (you will be given them on the exam). Know how to write equations from reactants (ionic reactants). Understand what solutions “look” like at a very magnified level.

Clicker Question When lead(II) nitrate and potassium iodide are mixed, which are the possible products? 1. PbI 2. PbI2 3. K(NO3)2 4. KNO3 a) 1 & 3 b) 1 & 4 c) 2 & 4 d) 2 & 3

Precipitation Reaction Determine the balanced chemical equation and net ionic equation when aqueous solutions of lead(II) nitrate and potassium iodide are mixed.

Solubility Rules