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

Chemistry Learning Center 2021 Chemistry Annex Chemistry TAs available from 9 am – 5pm Mondays – Fridays. Link to the schedule is on the website (Contact Information) Chemistry 202 TAs in the CLC: Mondays: 11am – 1 pm Wednesdays: 3 – 5 pm Thursdays: 1 – 3 pm

Lon-Capa 1st HW assignment due tonight by 10 pm. 1st “Quiz” (2nd HW) due Sunday, 9/10 by 10 pm. It will open today at 5 pm.

For Today Textbook Homework Videos Chapter 4: Solution Stoichiometry Precipitation Stoichiometry I: Net Ionic Equations Precipitation Stoichiometry II: Complete Equations Challenge Problem: Chapter 4 #121

For Monday Textbook Homework Chapter 5: 8, 15, 16, 26, 28, 29, 31, 119

James Scholar Opportunity REACT: is an outreach program that goes to elementary schools to teach students chemistry. September 11th, 12th, or the 13th at 6pm. 11th: 1027 Lincoln Hall 12th: 114 Transportation Building 13th: 319 Greg Hall Questions? Send an email to the REACT student president Samuel Cler at thereactprogram@gmail.com

Concentration of Vinegar? Knowing that vinegar is an aqueous solution that is 5.00% acetic acid [HC2H3O2(aq)] by mass and has a density of 1.01 g/mL, determine the concentration of vinegar in molarity.

NaHCO3(s) + HC2H3O2(aq) → NaC2H3O2 (aq) + H2O(l) + CO2(g) How Much Vinegar? NaHCO3(s) + HC2H3O2(aq) → NaC2H3O2 (aq) + H2O(l) + CO2(g) We have 10.5 g of baking soda. Knowing that vinegar is 0.841M acetic acid, determine the minimum volume of vinegar required for a complete reaction. [~149 mL]

Solubility Rules

Clicker Question A 15.0 g sample consisting of a mixture of silver nitrate and sodium nitrate is dissolved in water. This aqueous mixture then reacts with an excess of aqueous potassium chloride to form 3.97 g of solid. Calculate the percent by mass of silver nitrate in the first mixture.   a) 22.3% d) 72.9% b) 31.4% e) I cannot do this problem. c) 47.1%

Challenge Problem – Ch. 4

Clicker Question Consider mixing 150.0 mL of 0.125M solution of calcium nitrate with 150.0 mL of a 0.125M solution of sodium phosphate to produce a solid. Determine the mass of solid formed.   a) 0.844 g b) 1.94 g c) 2.53 g d) 3.88 g e) 5.82 g

Clicker Question Consider mixing 150.0 mL of 0.125M solution of calcium nitrate with 150.0 mL of a 0.125M solution of sodium phosphate to produce a solid. Determine the concentration of the phosphate ion after the precipitation reaction is complete.    a) 0.0104M d) 0.0625M b) 0.0208M e) 0 M c) 0.0417M

Challenge Problem – Ch. 4