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Chem 108: Lab Week 14

Chem 108: Lab Week 14. Sign in / Pick up Papers. Turn in Global Warming Questions Scantron. Divide raw score by 124 for percentage. Avg 71.9 % STD +/- 7.8%. Chem 108: Class/ Lab Acid-Base Titrations. 1) Fluid Exchange (Handout) Due Today 2) Acid-Base Equilibrium Experiment

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Chem 108: Lab Week 14

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  1. Chem 108: LabWeek 14 Sign in / Pick up Papers Turn in Global Warming Questions Scantron

  2. Divide raw score by 124 for percentage Avg 71.9 % STD +/- 7.8%

  3. Chem 108: Class/ Lab Acid-Base Titrations 1) Fluid Exchange (Handout) Due Today 2) Acid-Base Equilibrium Experiment (Handout) Due Today Post Lab & Guiding Questions (Submit on-line) http://chemconnections.org/general/chem108/Acid-Base%20Descriptions%20Guide.html http://chemconnections.org/general/chem108/Acids-Bases%20Guide.html

  4. Neutralization Reactions There is no difference in the stoichiometry of the reaction of acetic acid & HCl with NaOH, but there is a difference in pH . H+(aq) + OH -(aq) H2O(l)

  5. Aqueous Reactions: NeutralizationNet Ionic Equations HCl(aq) +NaOH (aq) NaCl (aq) + H2O(l) acid base salt water H+(aq) + OH -(aq) H2O(l)

  6. Aqueous Reactions: NeutralizationNet Ionic Equations CH3COOH(aq) +NaOH (aq)CH3COONa (aq) + H2O(l) CH3COO-(aq) + H+(aq) +Na+(aq) + OH-(aq)CH3COO-(aq) + Na+(aq) + H2O(l) acid base salt water Same Net Ionic Equation (NIE) for any neutralization Eg. H2SO42 H+(aq) + 2 OH -(aq) 2 H2O(l) H+(aq) + OH -(aq) H2O(l) __________________________ 2

  7. Acid-Base TitrationsNeutralization Chem 108 titration: phenolphthalein indicator Chem 120/121 pH Titration Curves

  8. Aqueous Reactions: NeutralizationpH @ the end point http://chemconnections.org/general/movies/pHofSaltSolutions.swf HCl(aq) +NaOH (aq) NaCl (aq) + H2O(l) pH = 7@ end pt. acid base salt water pH > 7@ end pt. CH3COOH(aq) +NaOH (aq)CH3COONa (aq) + H2O(l) acid base salt water

  9. Chem 108: Lab STANDARDIZATION Part 1- Standardization of NaOH Will NOT be done.

  10. https://www.youtube.com/watch?v=9DkB82xLvNE Acid-Base Titration Part 2: Unknown Acid

  11. Chem 108: LabPart 2: To Do (individually) today. Have signed before leaving lab. 0.2162 mol/L 3 trials must be within +/- 0.20 mL Take a clean, dry, 125 mL erlenmeyer flask to the stockroom window and get unknown acid solution. Record unknown number. Have data page signed before leaving lab today.

  12. Unkown Acid NeutralizationNet Ionic Equation/ Calculation HNO3(aq) +NaOH (aq) NaNO3(aq) + H2O(l) acid base salt water conj. acid conj. base acid base water • 25.00 mL of MH+ aq= ? (unknown acid solution) was titrated with a sodium hydroxide solution, MOH-= ? 0.2162 M. It required 24.20 mL as an average of three trials which were within +/- 0.20 mL to reach a faint pink color. • MH+ aq = ? H+(aq) + OH -(aq) H2O(l)

  13. Unkown Acid NeutralizationNet Ionic Equation/ Calculation acid base water • 25.00 mL of MH+ aq= ? (unknown acid solution) was titrated with a sodium hydroxide solution, MOH-= ? 0.2162 M. It required 24.20 mL as an average of three trials which were within +/- 0.20 mL to reach a faint pink color. ?MH+= [MOH- x VOH- / VH+ ] [? molH+ / ? molOH-] 0.2162molOH- x 0.02420LOH- x 1 molH+ LOH- x0.02500LH+x 1 molOH- = = 0.2093 MH+ H+(aq) + OH -(aq) H2O(l)

  14. QUESTION A 35.00 mL sample of a monoprotic acid of unknown concentration was titrated with 42.30 mL of 0.2250 M KOH. What is the concentration of the unknown acid? 0.0930 M 0.3030 M 0.2719 M 0.1860 M 0.3720 M

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