Lab Report 5 (The Heat of Ionization of a Weak Acid) -...

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Experiment # 5Experiment Title: THE HEAT OF IONIZATION OF A WEAK ACIDPre-lab/8Purpose/5Experimental Method/5Collection of Data/10Results and Calculations/32Accuracy/5Summary/3References/2Experimental Technique/10Report Presentation/10Special Initiative/insight/5Introduction:Thermodynamics is the study of energy changes in a system. This laboratory experiment is concerned with the thermo-chemical branch of this subject. The laws of thermodynamics describe the transfer of energy between systems, how they are conserved and how they are lost to
the surroundings of the system. This is quantitatively described by the laws of thermodynamics as well.Calorimetry is a method of measuring the heats and the energies of reactions by insulating the system from its surroundings, which prevents the heat loss from the system to the surroundings. In this experiment, a plastic cup will be used as an insulating system along with a cardboard top to completely cover and close the plastic cup calorimeter.Purpose:The purpose of this experiment was to calculate the heat of ionization of a weak acid by first calculating the enthalpy of neutralization of the strong acid strong base and enthalpy of neutralization of the undissociated weak acid with strong base. Using the value of KA and Ho ionization of the given weak acid, value of Goand Sowas also obtained.Experimental Method:A graduated cylinder was used to measure 50 mL of room temperature distilled water andthe water was transferred to the Styrofoam cup calorimeter- which was made of two Styrofoam cups placed within each other. A square piece of cardboard, with a hole fitted for a thermometer, was placed on top of the cup. The thermometer and calorimeter were left to stand until the temperature reading remained constant. The cardboard was removed and another 50 mL of distilled water from a hot water bath (at about 40oC) was added to the calorimeter, and the cardboard was quickly put back on the calorimeter so the heat would not escape. The temperature was measured from the moment the hot water was completely added, and was measured every 15 seconds from then on until a total of 4 minutes. The contents of the calorimeter were constantly stirred during and after the addition of the hot water by a stirring bar.
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The Styrofoam cup on the top and its contents were disposed of, and another clean Styrofoam cup was placed in the original cup. A graduated cylinder was used to measure 50 mL of NaOH solution and transferred to the calorimeter. The temperature of the solution and its concentration were recorded. In another graduated cylinder 50 mL of HCl were measured, a

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