ࡱ;   R F"䄾@CompObj\WordDocument7!ObjectPool!䄾!䄾 FMicrosoft Word 6.0 DocumentNB6WWord.Document.6;  Oh+'0  ! -9A IUr z5Science F:Microsoft Office:Microsoft Word 6:chem labLAB: TITLE OF LABsciencescience'@[w@Ngv`w@䄾@ܥhO e 7! 4VVVVVn xV" V&x X g"  @"  6&Lab: MOLECULAR MASS DETERMINATION FROM BOILING POINT  Introduction In this lab, you will measure and 1) compare the boiling point of pure water and the boiling point of a solution of water and sugar, 2) calculate the molecular mass of the sugar from your boiling point data and 3) calculate a percent error for molecular mass. MATERIALS: 125 mL Erlenmeyer flask iron ring dextrose wire gauze thread clamp distilled water thermometer ring stand Bunsen burner Procedure 1. Obtain the mass of a clean dry 125-mL Erlenmeyer flask. Fill it with 50.0g of distilled water. Set up the equipment shown below. Do not let the thermometer touch the side of the bottom of the flask. 2. Heat the water to the boiling point and maintain a constant temperature for two minutes. Record the temperature of the water to the nearest 0.5oC. 3. Prepare a solution of 10.0g of dextrose, C6H12O6, in 50.0g of distilled water. Heat this solution to the boiling point and maintain a constant temperature for two minutes. Do not let the thermometer touch the side or the bottom of the flask. Record the boiling point of the solution to the nearest 0.5oC. 4. Calculate the molecular mass of the sucrose from this boiling point data. Data MASS OF FLASK EMPTYMASS OF FLASK WITH DISTILLED WATERTEMPERATURE OF BOILING WATERMASS OF FLASK WITH WATER (2nd trial with sugar)MASS OF SUGARTEMPERATURE OF BOILING SUGAR SOLUTION Calculations 1. Calculate the change in the boiling point, i.e., the difference between the boiling point of pure water and the boiling point of the solution of sugar and water. 2. Recall that T =kbpm where T is the change in boiling point, kbp is the boiling point constant and m is the molality of the solution (for water kbp = 0.52oC/1m/kg). Calculate the molality of the sugar solution 3. Recall that the definition of molality is m = moles of solute kg of solvent You have determined the molality from the boiling point data. You know the grams of solvent which you can translate to kilograms and you know the grams of solute. Determine the molecular mass of the sugar. 4. The molecular formula for the dextrose is C6H12O6. Determine the percent error in your experiment. 5. If CaCl2 had been used in this experiment, what would have been the effect on the boiling point? Why? Analysis Write a conclusion. SOLUTIONS Name: _______________________ Partner #1: _______________________ Partner #2: _______________________ Acton-Boxborough Regional High School Due Date: ______________________ Acton-Boxborough Regional High School  |HH(EG(HH(d'`|HH(EG(HH(d'` |HH(EG(HH(d'`00&ta0`0(00&00&00&00&00&ࡱ; SummaryInformation(Microsoft Word 6.0.19ࡱ; <=>?LWX+,JK}~       - R w nuU]cU]cU]c]^V]UZ]]h]h uDa]uD]a UZ]c(G<>LMST_\*$$$,$$$$$$$$$$$$$,$,$,$,$,$,$,$,$,,,,,lH$ h&*+,IJK|}~5 t u v U d e , ,,,,,,,,,,,,,$$$$$,$,$$$$$$$$$$$$$$$lH$ lH$ $    w  , - $$$$$$$$,$$$$$$$$$$$$$$$$$$$$$$$$$$$T$T h !s0h !sh%- t u v w $h 0 !lK@Normal]a "A@"Default Paragraph Font @ Header ! @ Footer !*O"* Chem HeaderL UZ]c   /D sn * - <> N~>&science-Science F:Teacher Folders:Murphree:MOLAR MASSscience-Science F:Teacher Folders:Murphree:MOLAR MASSscience.Science F:Teacher Folders:Murphree:MM from BP science.Science F:Teacher Folders:Murphree:MM from BP science.Science F:Teacher Folders:Murphree:MM from BP science.Science F:Teacher Folders:Murphree:MM from BP science.Science F:Teacher Folders:Murphree:MM from BP science.Science F:Teacher Folders:Murphree:MM from BP science.Science F:Teacher Folders:Murphree:MM from BP science.Science F:Teacher Folders:Murphree:MM from BP @VMTimes New Roman Symbol MArial MTimesMNew Century Schlbk"1h3:c4& 3 #9g4Science F:Microsoft Office:Microsoft Word 6:chem labLAB: TITLE OF LABsciencescienceࡱ;