Experiment 14 Vapor Pressure and the Heat of Vaporization Chemistry 1220 September 2nd 2013 Raffeal Bennett Purpose The purpose of the this experiment was to use the Clausis Clapeyron equation to calculate the heat of vaporization by using experimental techniques to record temperature and volume in compounds in which the liquid and gas are in equilibrium and by determining those boiling points Procedure Refer to pages 8 10 of General Chemistry 1220 Laboratory Manual by Hayden McNeil Publishing 2014 Calculations Please see attached calculations Graphs Please see attached graphs Conclusion The heat of vaporization can be determined by using the Clausisus Clapeyron equation However to do so the temperature and pressure of a substance over a certain time must be measured The substance is heated changing the pressure which causes a pressure change To obtain the pressure at a specific temperature the barometric pressure is multiplied by the difference of one and the ratio of the volume of the substance at room temperature to the volume at that specific temperature times the ratio of the specific temperature and the room temperature By graphing the natural log of all the pressure against one over the temperature a temperature slope can be formed that can be multiplied by the universal gas constant to yield the heat of vaporization This was experimentally performed for octane methanol and ethanol All three were graphed on a natural log of pressure versus one over temperature graph Graphically the heat of vaporization for the unknown compound was the highest followed by ethanol octane and then methanol The whole process can be used for unknown substances In this experiment the unknown substances boiling point was 63 5 degrees Celsius The boiling point is the lowest one out of all the compounds measured as seen in the report sheet There were a few possible errors that could have cause inaccuracies in this experiment The uncertainties of the equipment the volume was plus or minus 1mL the temperature was plus or minus 1 degrees Celsius and the pressure was plus or minus 1 mmHg Another was could have been the friction between the plunger and syringe that caused the vapor to escape in my known compound of Octane and made my results wrong Using the Clausius Clapeyron equation Octane Heptane and Hexane were successfully graphed however it was not in the proper order according to their actual boiling points and heats of vaporization The slope of octane should have had the smallest slope but instead had the largest one showing that the data measured during the laboratory was not correct Additionally the graph of an unknown substance was successfully created and compared to the other substances Lastly the boiling point of an unknown compound was determined and again compared to the known compound s boiling points