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AP Chem Lab 9 Acid Base Lab.docx

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Department
Chemistry
Course
CHEM 1951
Professor
Dr.Acio
Semester
Summer

Description
Curt Kim, Jonathan Lee, Keshav Mantha, Bobbie Sheng AP Chemistry, Period 1 4/1/13 Title: Antacid Analysis Goal: To determine the neutralizing effectiveness per gram of commercial antacid Procedure: First, four different antacids were pulverized using a mortar and pestle: Alka- Seltzer, Tums, Rolaids, and Maalox. One brand of antacid was then massed to 0.2 (or 0.199) grams and placed in an Erlenmeyer flask. 25mL of 0.1M hydrochloric acid was added to the flask and stirred. The flask was then heated on a hot plate until it boiled, and six drops of bromophenol blue indicator were added. A buret with about 75mL of 0.1M sodium hydroxide was then prepared, and the NaOH was titrated into the flask containing the cooled HCl-antacid mixture until the indicator reached a light blue color. The volume of the NaOH solution left over in the buret was then recorded. Two trials of this process were done for each antacid. Data: Alka Seltzer Tums Trial 1 Trial 2 Trial 1 Trial2 Mass of antacid sample (g) .199 .199 .199 .199 Volume of HCl added (mL) 25 25 25 25 Molar concentration of HCl (M) .1 .1 .1 .1 Molar concentration of NaOH .1 .1 .1 .1 (M) Initial Buret Reading (mL) 0 0 0 0 Final Buret Reading (mL) 12.77 12.72 9.77 9.51 Volume of NaOH (mL) 12.77 12.72 9.77 9.51 Maalox Rolaid Trial 1 Trial 2 Trial 1 Trial2 Mass of antacid sample (g) 0.199 0.201 0.199 0.200 Volume of HCl added (mL) 25 25 25 25 Molar concentration of HCl (M) .1 .1 .1 .1 Molar concentration of NaOH .1 .1 .1 1 (M) Initial Buret Reading (mL) 0 0 0 0 Final Buret Reading (mL) 8.1 9.4 7.8 8.0 Volume of NaOH (mL) 8.1 9.4 7.8 8.0 Data Analysis: Alka Seltzer Tums Trial 1 Trial 2 Trial 1 Trial 2 Amount of HCl added (mol) .0025 .0025 .0025 .0025 Amount of NaOH added (mol) .001277 .001272 .000977 .000951 Amount of base in antacid sample .001223 .001228 .001523 .001549 (mol) mol base in antacid/mass of .0061457286 .006170854 .0076532663 .0077839196 antacid sample (mol/g) 3 Average mol base in antacid/mass .0061582915 .0077185930 of antacid sample (mol/g) Cost per gram of antacid (cents/g) 5.135459534 4.702723846 antacid effectiveness (mol base in.0011991705 .0016413026 antacid/cent) Amount of HCl added = Volume of HCl solution * Concentration of HCl solution All Trials of Alka Seltzer and Tums: .025L * .1M = .0025 mol HCl Amount of NaOH added = Volume of NaOH solution * Concentration of NaOH solution Alka Seltzer Trial 1: .01277L * .1M = .001277 mol NaOH Alka Seltzer Trial 2: .01272L * .1M = .001272 mol NaOH Tums Trial 1: .00977L * .1M = .000977 mol NaOH Tums Trial 2: .00951L * .1M = .000951 mol NaOH Amount of base in antacid sample = Amount of HCl - Amount of NaOH Alka Seltzer Trial 1: .0025 mol - .001277 mol = .001223 mol Alka Seltzer Trial 2: .0025 mol - .001272 mol = .001228 mol Tums Trial 1: .0025 mol - .000977 mol = .001523 mol Tums Trial 2: .0025 mol - .000951 mol = .001549 mol Mol base in antacid/Mass of antacid sample Alka Seltzer Trial 1: .001223 mol/.199g = .0061457286 mol/g Alka Seltzer Trial 2: .001228 mol/.199g = .0061708543 mol/g Alka Seltzer Average: (.0061457286 mol/g + .0061708543 mol/g)/2 =.0061582915 mol/g Tums Trial 1: .001523 mol/.199g = .0076532663 mol/g Tums Trial 2: .001549 mol/.199g = .0077839196 mol/g Tums Average: (.0076532663 mol/g + .0077839196 mol/g)/2 = .0077185930 mol/g Cost per gram of antacid = (price per bottle/number of tablets per bottle)/mass of tablet Alka Seltzer: (599 cents/36) / 3.24g = 5.135459534 cents/g Tums: (529 cents/86) / 1.308g = 4.702723846 cents/g *Prices and the average masses for each tablet were found online and may be slightly off Antacid effectiveness = (Average mol base in antacid/mass of antacid sample)/(Cost per gram of antacid) Alka Seltzer: (.0061582915 mol/g)/(5.135459534 cents/g) = .0011991705 mol/cents Tums: (.0077185930 mol/g)/(4.702723846 cents/g) = .0016413026 mol/cents Maalox Rolaids Trial 1 Trial 2 Trial 1 Trial 2 Amount of HCl added (mol) .0025 .0025 .0025 .0025 Amount of NaOH added (mol) .00081 .00094 .00078 .00080 Amount of base in antacid sample .00169 .00156 .00172 .00170 (mol) mol base in antacid/mass of antacid sample (mol/g) Average mol base in antacid/mass of antacid sample (mol/g) Cost per gram of antacid (cents/g) 4.435555556 2.075055188 antacid effectiveness (mol base in antacid/cent) Amount of HCl added = Volume of HCl solution * Concentration of HCl solution All Trials of Maalox and Rolaids: .025L * .1M = .0025 mol HCl Amount of NaOH added = Volume of NaOH solution * Concentration of NaOH solution Maalox Trial 1: .0081L * .1M = .00081 mol NaOH Maalox Trial 2: .0094L * .1M = .00094 mol NaOH Rolaids Trial 1: .0078L * .1M = .00078 mol NaOH Rolaids Trial 2: .0080L * .1M = .00080 mol NaOH Amount of base in antacid sample = Amount of HCl - Amount of NaOH Maalox Trial 1: .0025 mol - .00081 mol = .00169 mol Maalox Trial 2: .0025 mol - .00094 mol = .00156 mol Rolaids Trial 1: .0025 mol - .00078 mol = .00172 mol Rolaids Trial 2: .0025 mol - .00080 mol = .00170 mol Mol base in antacid/Mass of antacid sample Maalox Trial 1: .00169 mol/.199g = .0084924623 mol/g Maalox Trial 2: .00156 mol/.201g = .007761194 mol/g Maalox Average: (.0084924623 mol/g + .007761194 mol/g)/2 = .81268282 mol/g Rolaids Trial 1: .00172 mol/.199g = .0086432161 mol/g Rolaids Trial 2: .00170 mol/.200g = .0085 mol/g Rolaids Average: (.0086432161 mol/g + .0085 mol/g)/2 = .0085716081 mol/g Cost per gram of antacid = (price per bottle/number of tablets per bottle)/mass of tablet Maalox: (499 cents/90)/ 1.25 g = 4.435555556 cents/g Rolaids: (519 cents/100)/ 1.51g = 3.437086093 cents/g *Prices and the average masses for each tablet were found online and may be slightly off Antacid effectiveness = (Average mol base in antacid/mass of antacid sample)/(Cost per gram of antacid) Maalox: (.81268282 mol/g)/(4.435555556 cents/g) = .001832200746 mol/cents Rolaids: (.0085716081 mol/g)/(3.437086093 cents/g) = .002493859 mol/cents Rolaids
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