# 11Post - CHE 133 MAKE-UP LABORATORY EXERCISE MONDAY...

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1 Determination of NaHCO 3 Part 1 - Gasometric in a Mixture Last Update: 11/15/2007 2:42 PM CHE 133 MAKE-UP LABORATORY EXERCISE MONDAY, DEC 10, 2007 - Starting 5:00 PM Eligible Students are ONLY those who have EXCUSED ABSENCES from : ONE or MORE TEST EXERCISES or TWO or MORE PRELIMINARY EXERCISES MUST SIGN UP WITH DR. AKHTAR BY DEC 7 Final Quiz will be given at the beginning of the check-out laboratory meeting CHE 133 Lectures and Labs will not meet next week – Nov 19, 20, 21 Help sessions will meet in accordance with adjusted schedule. Purpose: Determine the percent of NaHCO 3 in a mixture by Gasometry Concepts: Ideal Gas Law Henry’s Law Vapor Pressure Stoichiometry Techniques: Capture Gaseous Product Corrections to volume Apparatus: Syringe Thermometer Barometer The Exercise is Conceptually Simple . 1. Weigh Sample, w Sample . 2. Do Chemistry: NaHCO 3 (s) + H + (aq) Na + (aq) + H 2 O (l) + CO 2 (g) 3. Capture Liberated Gas and Measure its volume, v CO2 P v = n R T to get number of moles of CO 2 n CO2 = P CO2 v CO2 / RT 4. Use Ideal Gas Law 5. From the Stoichiometry of the reaction, get moles, of NaHCO 3 n NaHCO3 = n CO2 6. From number of moles, get weight w NaHCO3 = n NaHCO3 * 84.0 g / mol 7. Compute Percent Composition of Sample Pct NaHCO3 = 100 * w NaHCO3 / w Sample The unknowns consist of a uniform mixture of NaHCO 3 and NaCl

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2 But - it Involves Some Important Concepts Limiting Reagents Gas Mixtures – Partial Pressure Gas Solubility – Henry’s Law Departure of CO 2 from Ideality Reproducibility The Basic Experimental Arrangement NaHCO 3 HCl Syringe Limiting Reagent: Suppose the unknown is 100% NaHCO 3 You are asked to weigh 0.2 – 0.3 g of the unknown. What is the maximum volume of CO 2 we can expect?
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## This note was uploaded on 10/25/2008 for the course CHE 133 taught by Professor Robertschneider during the Spring '08 term at SUNY Stony Brook.

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11Post - CHE 133 MAKE-UP LABORATORY EXERCISE MONDAY...

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