- Information
- AI Chat
Calomitry experiment
Civil Engineering
Bicol University
Recommended for you
Related documents
Preview text
Calorimetry Jhon Armand M. Hermonda Department of Mechanical Engineering, University of San Carlos Abstract This report is about Calorimetry in where it carried out to determine whether reaction is endothermic or exothermic using temperature changes observed and carry out determination of the heats of the reaction using an improvised calorimeter. 3 types of experiment were done, determination of the calorimeter constant, heat of solution, and determination of heat of neutralization. The 1st experiment was an improvised calorimeter was used which is a Styrofoam coffee cups, a cold water was put inside it followed a distilled water after 3 minutes of boiling, then calculate the heat changes. The 2 nd experiment was an ammonium chloride in distilled water put in the improved calorimeter and was to determine if it is endothermic or exothermic. The last experiment was a Hydrochloric acid mixed in Sodium Hydroxide after the it is done, calculation was done to find the heat that flowed from the reaction into the water of the reactant solution or vice versa, the number of moles of each reactant and the number of moles of each product and the change of heat in terms of kilojoules per mole. The experiments done exhibits experience of errors in the process and close and far percent of error from the theoretical value. Introduction During the events in which physical changes and chemical reactions take place, energy changes also always occur alongside it, which is observed as the heat flow into or out of the system. An endothermic process requires the absorption of heat, while an exothermic process releases heat. The measurement of heat changes in physical and chemical processes is called calorimetry, in which the heat flow for a process is measured with the use of an instrument known as calorimeter. To prevent heat loss or gain between the instrument and its surroundings, the calorimeter is insulated. A weighed amount of water which serves as the heat sink is contained, and monitoring of the temperature is done when the process involving the study is performed within the calorimeter. The quantity of heat transferred the process is determined from the mass of water in the calorimeter and the changes in the temperature. To calculate the quantity of heat energy that transfers during the physical or chemical process, the values of the temperature changes undergone the water are used. The quantity of heat which is involved in the temperature change, Q, is given the following formula: Q where m is determined as the mass of the water, C is the specific heat of water (4 J g 1 C ), and represents the change in temperature. The following experiment makes use of a simple calorimeter made from two nested Styrofoam coffee cups. There are still ways which some heat transfer can take place, despite the Styrofoam cup being a good insulator. A calorimeter constant is determined to make corrections for these, which will be used for the experiment. Methodology A. Determination of the Calorimeter Constant. An improvised calorimeter was assembled an insertion of Styrofoam cover into two dry Styrofoam coffee cups. A thermometer and a glass stirrer were inserted into the Styrofoam cover. Heat loss ensured to be minimal from the entry points. The improvised calorimeter was placed into a 250 mL beaker to stabilize the 25 mL of cold water was measured with a graduated cylinder and put into the calorimeter and covered with the apparatus. Distilled water in a beaker was heated until it reaches 25 mL measured and put in a dry beaker. It was left standing for about 3 min standing with occasional stirring. The temperature of both hot water in the beaker and the cold water in the calorimeter was measured. The lid of the calorimeter was removed and the hot water quickly poured inside. It was immediately covered and stirred for 30 seconds. The temperature of water in the calorimeter was monitored. The highest and temperature reached the water was recorded. From the two temperature changes and the masses of the hot and cold water, calorimeter constant (C) was calculated. B. Heat of Solution Cold Water 44 9 35 (25)(4)(35) 3661 3 kJ Hot Water J this calculations, calculate calorimetry constant was made possible. The formula of the (q Hot qCold ) calorimetry constant is . ( T ) cold 3661 35 J kJ C The calorimetry constant is C which means that our data collected is good and just think also that there are no negative calorimetry constant and since the data is close to negative probably it encounters few errors. B. Heat of Solution Volume of Cold Water Temperature of water Mass of NH4Cl Temperature Reached Amount of Heat Transferred Experimental Molar Heat of Solution Theoretical Molar Heat of Solution Percent error of Molar Heat Table 2: Heat of Solution Values 25 mL 22 2 g 21 0 KJ 2 14 85 The NH4Cl, a white powdered substance, dissolved as it was added and stirred in cold water. To calculate for the amount of heat transferred or evolved during this process, the formula used was qreaction which was derived from qcalorimetry (qsolution qreaction) 0. The resulting calorimeter constant from part A is used in the calculations. The value used for specific heat was that of (4 The value for mass was the sum of the masses of cold water and NH4Cl which was 28 g. The mass of water is assumed to be 25 g following that density is 1 q reaction J ( 4 J ( ) ( 28 g ) ) ) ( ) The amount of heat that transferred during the dissolving process was 0 KJ. In which it was obtained multiplying the calculated result (117 J) to 1 J and its principles of significant figures. Positive value indicates that the dissolution was an endothermic process. It coincides with the decrease in temperature of the solution. NH 4Cl absorbed heat from its surroundings as it dissolved in the water solvent. To get the molar heat of the reaction, the molar mass of the salt must be known. With the molar mass of NH4Cl, which is 53 its number of moles we can continue solve for it through 1 mol conversion ( 2 g NH 4 Cl x ), which results to .055 moles NH4Cl. With this value, the 53 g molar heat can now be calculated. q reaction moles NH 4 Cl 0 KJ moles NH 4 Cl The in the given data is 2 This experimental value was compared to the theoretical value of molar heat of NH4Cl calculating for the percent error. The formula for x 100 in which our theoretical value is 14 percent error is: theoret ical The result is error which would imply that the experimental value was far from the theoretical value. It would also imply the presence of errors. The errors may have been from the performance of the experiment such as inaccurate measurement of values and temperature and spillage in transferring the solute to the calorimeter. Error may have can also be related to the calorimeter constant for its close to negative next to 0. C. Determination of Heat of Neutralization Volume of 3 M NaOH Temperature of NaOH Volume of 3 M HCl Temperature of HCl Maximum Temperature Reached 25 mL 30 25 mL 30 46 The molar heat of the reaction was The experimental value for molar heat of HCl was compared to the theoretical value for molar heat of HCl calculating for its percent error. k J kJ ) kJ The result showed an for experimental value of molar heat. The quite far value of percent error would imply the experiment had a few errors on its process. This error might be inaccuracy, inexperience handling equipment, and spillage of the sample. Conclusion The calorimeter constant of the improvised coffee cup was 2 which quite close to negative which is next to zero thus, a lot of errors may encounter. The dissolution process of NH4Cl was endothermic since it had a heat transfer value (0 KJ) that is greater than zero. the values of the amount of heat absorbed and the number of moles of NH4Cl, the molar heat was computed. The amount of 2 which gives us a percent which it means we encountered too many errors in this segment of experiment. The heat neutralization of the sample NaOH and HCl acid solution was endothermic base on our data computed kJ). This leads us finding our percent error which is that is away from the ideal theoretical value. This experiments encountered quite a lot of errors in the process which are inaccuracy of the measurement (temperature, weight, volume), spillage of powder and liquid samples, and inexperience handling of equipment. Recommendations for the future experiments like this or not is to observe proper handling in equipment, precise measuring, and cautious in transferring samples. References (1) Calorimeter. (accessed Dec 5, 2018). (2) John Brennan. How to Determine a Calorimeter Constant. (accessed Dec 5, 2018). (3) (accessed Dec 5, 2018). (4) momorae0 OF NEUTRALISATION. (accessed Dec 5, 2018).
Calomitry experiment
Course: Civil Engineering
University: Bicol University
- Discover more from:Civil EngineeringBicol University999+ Documents
- More from:Civil EngineeringBicol University999+ Documents
