experiment 25 report sheet calorimetry

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CHEM 112 Exp: 25 Calorimetry CHEM 112 Farnum 11:30 AM Experiment: 25 Calorimetry Conclusion: In conclusion, for part B, my average for my NaOH HCl reaction was my standard deviation was 0, my relative standard error was 0, and my percent error was For my NaOH HNO3 reaction my average was my standard deviation was 1, my relative standard deviation was 1, and my percent error was In part C, my unknown was 21, its heat capacity was and based on the chart in the lab book my unknown salt was Na2SO4. The average total per mole of the unknown salt was my standard deviation was 372, my relative standard deviation was 4, and my percent error was CHEM 112 Exp: 25 Calorimetry Experiment: Calorimetry Abstract The purpose of this experiment was to perform a calorimetry experiment with the use of a coffee cup calorimeter apparatus to observe the temperature change of a chemical reaction. We use a double coffee cup calorimeter to prevent the heat generated within the apparatus from being lost to the surroundings. Within all physical reactions there is a transfer of heat that is either released as an exothermic reaction or absorbed as an endothermic reaction. This transfer of heat is expressed as enthalpy of a reaction, when these values are negative this represents an exothermic reaction whereas a positive represents an endothermic reaction. Our goal is to determine the enthalpy of neutralization of a strong reaction and to determine the enthalpy of a solution for the dissolution of a salt. The enthalpy of a neutralization reaction is when a strong acid and a strong base are mixed together to produce heat and water as an exothermic reaction, it is in the form of the energy released per mole of water. As for a salt, once it dissolves in water, the energy will be absorbed or released depending on its lattice and hydration energy of its ions, its unit is in of a salt. The major results for this experiment is that for my reactions the most important data was that for my HCl acid my average was my standard deviation was 0, my relative standard error was 0, and my percent error was As for my HNO3 my average was my standard deviation was 1, and my percent error was My results for the acid base reactions were high indicating I did not have accurate and precise data. As for part C, the average total per mole of the unknown salt was my standard deviation was 372, my relative standard deviation was 4, and my percent error was Experiment: Calorimetry Introduction The goal of this experiment was to determine the enthalpy of the neutralization for an reaction and to determine the enthalpy of solution for the dissolution of a salt. The specific heat of a substance can be expressed as the energy required to change the temperature of one gram of a substance whereas the molar heat capacity is defined as the amount of heat required to raise the temperature of one mole of a substance one degree in either Celsius or Kelvin. This is determined finding the amount of heat that was gained the water, the mass of the sample being tested, and the change of temperature of a sample. Specific heat is an intensive property, an intensive property is a property that does not change even where the mass or volume changes because they represent elemental characteristics that help us define a substance. Physical and chemical reactions transfer either as an exothermic or endothermic reaction. Endothermic reactions are events in which energy is evolved and endothermic reactions are events in which energy is absorbed. A calorimeter is an apparatus that allows us to measure the amount and the flow of heat through a system and its surroundings caused either a chemical or physical reaction. Calorimetry is used because we can assume the apparatus itself is a perfect insulator and because we can use it to measure the energy transfer in a process using an isolated system. There are two different types of calorimeters, a bomb calorimeter and a coffee cup calorimeter which is the type of calorimeter we will use in this experiment. A bomb calorimeter is a metal container in which the CHEM 112 Exp: 25 Calorimetry Na2SO4 (s) 2H2O (l) 2NaOH (aq) H2SO4 (aq) Equations: Heat mass Cv qsystem qlost object water Enthalpy of neutralization (at constant pressure and volume) Methods We prepared the calorimeter obtaining two Styrofoam coffee cups to prepare the apparatus followed a Styrofoam lid, stirrer, and a digital thermometer using a Pasco Capstone system to acquire our data. The reason we use Styrofoam is because it is a good insulator and it insulates the inside from the outside. If we had used a different material or possibly a single cup instead of two, then there is a higher chance that there will not be enough insulation and some of the heat will be lost. So, for this experiment we are to assume that our coffee cup calorimeter is a insulator. Since we used the digital thermometer we did not need to observe the change in temperature every few seconds, instead we let the system run continuously and it recorded our data over time. I believe that using this method we can get more accurate readings giving us better results because of the fact that it removes any personal error. For the first part of Part B I took 50ml of 0 NaOH and measured its temperature alone in the coffee cup calorimeter for about three minutes continuously. After three minutes I added 50ml of 1 HCl to the cup with the NaOH and measured the change in temperature for an additional 5 minutes. I then repeated this process for a second trial, and then an additional two trials but with a mixture of NaOH and HNO3. After we plotted our data on graphs. For part C, I collected of my unknown salt and 20ml of DI water. With the digital thermometer, I measured the initial temperature of the of the DI water itself in the calorimeter for three minutes. After the three minutes, I added my unknown salt and continuously measured the change in temperature of the reaction for another 5 minutes. I did this for two trials with my salt. After collecting the data, we made additional graphs for this data. The procedures for these experiments were both produced Beran, J. Laboratory Manual for the Principles of General Chemistry. (10th John Wiley Sons, Inc. USA, pp Data CHEM 112 Exp: 25 Calorimetry Enthalpy of Neutralization for an Acid and Base Reaction Reaction HCl NaOH HNO3 NaOH Trial 1 2 1 2 Volume of Acid 50 50 50 50 (mL) Volume of Base 50 50 50 50 (mL) Temperature of 22 22 22 23 Acid Temperature of 22 22 22 23 Base Final Tmax from 30 30 30 30 Graph Enthalpy of Solution for the Dissolution of a salt Reaction H2O Na2SO4 Trial 1 2 Mass of Salt (g) Moles of Salt (mol) 5 0 5 0 Mass of water (g) Initial Temperature of Base 20 23 20 23 Final Temperature of mixture from 26 26 Graph The tables above show the data collected for the neutralization of the acid base reactions and the solution for the dissolution of a salt. The acid base reactions were HCl NaOH and HNO3 NaOH. My unknown salt for part C was Na2SO4. These values were used to calculate the heat transferred and the enthalpy of neutralization. CHEM 112 Exp: 25 Calorimetry The graphs above represent the reaction of HNO3 NaOH. You can see based on the graph that as I added the HCl there was a dramatic spike in both graphs just as there had been in the previous two graphs. The reaction was almost instant as well, the horizontal line at the top represents the max temperature of my chemical reaction. CHEM 112 Exp: 25 Calorimetry These graphs represent my enthalpy of a dissolution of a salt, which is a reaction between my unknown salt Na2SO4 and water. The temperature change was also fairly rapid compared to my acid base reactions but just a bit slower. The temperature for this reaction is also increasing, indicating that I had an exothermic reaction, a release of CHEM 112 Exp: 25 Calorimetry Heat change of Salt Total Enthalpy Change Cs 13 14 Cw 267 284 7532 8059 Cs of Dissolution H2O) Average of Dissolution 7796 H2O) Part C Results Standard Deviation Relative Standard Deviation Error N2SO4 372 4 297 The tables above represent the calculated results for the enthalpy of neutralization of an acid and base reaction and for the dissolution of a salt. Discussion In this experiment, we were expected to determine the enthalpy of neutralization for an reaction and the enthalpy of solution for the dissolution of a salt. We know that the specific heat is what causes the temperature of a gram of a substance to rise We use a calorimeter, which is an apparatus that allows us to measure the flow of energy through a system and its surroundings, to determine this because we know the specific heat capacity of water. The calorimeter is the best apparatus to use because it acts as a perfect insulator preventing heat from escaping into the surroundings, where in this instance the energy is equal to the heat. For part B, we determined the enthalpy of the neutralization reaction with the known values of our change in temperature and the molarity of our acids and bases. My chemical reactions data for my HCl acid was that my average was my standard deviation was 0, my relative standard error was 0, and my percent error was My standard deviation and relative was okay because they were under one, nut my percent error is way too high. It is abouve which means that my data was not accurate and precise. Anything below is considered good data. For my HNO3 my average was 68 my standard deviation was 1, my relative standard deviation was 1, and my percent error was these results are also above which means that these results are not accurate as well. Overall, I have good quality data for my experiment indicating that my errors had an impact on my results. I had could have possibly lacked technique or maybe possible that my lack of consistency with the mixing impacted my results. For part C, we determined the enthalpy od solution for the dissolution of a salt. Lattice energy and hydration energy are very important factors in this experiment. Lattice energy is the energy required to break the ionic bonds within a solid and our hydration energy has to do with the ions that bond with water molecules that creates forces. My unknown was 21and its heat capacity was This specific heat capacity tells me that my unknown salt was Na2SO4. The average total per mole of the unknown salt was my standard deviation was CHEM 112 Exp: 25 Calorimetry 372, my relative standard deviation was and my percent error was We see a high percent error because there is a low value and low temperature change, even the smallest errors could affect the results. It is so high because even though we assume our calorimeter is we know that it is indeed not a perfect insulator. Conclusion In conclusion, for part B, my average for my NaOH HCl reaction was my standard deviation was 0, my relative standard error was 0, and my percent error was For my NaOH HNO3 reaction my average was my standard deviation was 1, my relative standard deviation was 1, and my percent error was In part C, my unknown was 21, its heat capacity was and based on the chart in the lab book my unknown salt was Na2SO4. The average total per mole of the unknown salt was my standard deviation was 372, my relative standard deviation was 4, and my percent error was Errors Errors that occurred throughout my experiment was that I accidentally mixed my acids and bases incorrectly for part A which resulted in almost no reaction. At first I understand why I had no reaction but after performing the experiment a second time I realized I had mixed the incorrect reagents. Another error that occurred was that I was not consistent with stirring for both parts, this could have affected the rate of the reaction affecting my results. Errors that could have occurred could have been that I splashed some of the water out of my calorimeter. This would be a problem because it would affect the mass of my water and my data will account for more mass of water than there was present. A second error that could have occurred could have been that I had a hole in my calorimeter and I failed to notice, this would be an error because then my experiment would not have been properly insulated. If it is not properly insulated then some of the heat can escape and the temperature would no longer be a constant.

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Course : General Chemistry (CHEM 112)

University : citrus college.

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Question: Experiment 25 Report Sheet Calorimetry Date Lab Sec Name Desk No. A. Specific Heat of a Metal Unknown No. Trial 1 Trial 2 1. Mass of metal (8) 2. Temperature of metal (boiling water) (°C) 99.10°c 20.477g 14.654g 94.00°C 60.299g 60.5919 79.4459 44 79.7739 3. Mass of calorimeter (g) 4. Mass of calorimeter + water (8) 5. Mass of water (g) 20.800 21.50°C 6.

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To find the temperature change of the water, subtract the initial temperature of the water, C, from the maximum temperature of the metal and water, C.