Heat of Reaction and Solution - 2750 Words

Heat of Reaction and Solution (Lab Report Sample) Content: Studentà ¢Ã¢â€š ¬Ã¢â€ž ¢s Name Professorà ¢Ã¢â€š ¬Ã¢â€ž ¢s Name Course Date Heat of Reaction and Solution Purpose The main aim of this experiment was to determine the energy between initial and final states of a solution. In this lab, both exothermic and endothermic processes were illustrated. The lab also aimed at measuring the amount of heat absorbed or dissolved in various reactions. Introduction Calorimetry is a technique where the heat effect of a given procedure can be measured, with this procedure being a physical or chemical change such as acid-base neutralization. The instrument used is a calorimeter, which can directly measure temperature, thus determining heat effect. Calorimetry is utilized in thermochemistry for the determination of enthalpy and heat capacity among other properties (David 100). Further, energy measurement is a way to analyze the relationship between the properties of a material and energy structure. Enthalpy, H, is given by the following formula: H= U+PV, Where U is the internal energy, P the pressure, and V is the volume of the system, and H is the heat at a constant pressure. Enthalpy changes are used to directly study thermodynamic effects. In this case, a Styrofoam cup calorimeter (calorimetry with constant pressure) was applied. The relations between an amount measured in this calorimeter and the heat effect produced (heat balance equation) are used to give temperature as a function of generated heat from the calorimeter. In chemical processes, energy differences are mostly observed between the final and initial states due to either heat absorption (endothermic processes) or heat production (exothermic processes) (Hundsdorfer 102). In this experiment, both cases are depicted using the following reactions CITATION Dav10 \l 1033 : 252412551625500HClaq+NaOHaq H2 O+NaClaq(1) 263842543053000HNO3aq+NaOHaq H2 O+NaNO3aq(2) 263842541211500CH3CO2Haq+NaOHaq H2 O+CH3CO2Naaq(3) 252412545021500KNO3s+34H2 Ol KNO334H2 O3(4) Where (aq) indicates a substance in aqueous solution, (l) a liquid, and (s) a solid. Reactions 1-3 are between acids and bases (neutralizations) with acids in equations 1 and 2 being strong and weak in 3. Further, there is enthalpy of solution, also known as heat of solution in reaction 4 since heat is absorbed at constant pressure (Calvet and Henri 54). In an exothermic process where heat is released, the enthalpy H is negative, while in an endothermic one, the enthalpy is positive. The units of H are given as cal/mole of one of the reactants used or a product consumed. The heat of solution H can be given as: qcalorimeter=wsaltcsalttf-ti+wwatercwaterti-t2 With the specific heat and amount of KNO3 being small, the equation can be simplified to: qcalorimeter=wwatercwater(tf-t2) but qreaction= -qcalorimeter so qcalorimeter= -wwatercwater(tf-t2) Heat produced in an exothermic process goes to the water in which the products are dissolved. It is noteworthy that the calorimeter determines the warmth of the water. The amount of heat produced is as a result of a given temperature change and can be solved by applying the heat capacity equation below: Heat change = m C T(units are joules) Where heat is the product of mass(m), specific heat capacity(C), and temperature change(T), The energy between the initial and final states can, thus, be determined. Also, both exothermic and endothermic processes can be illustrated, and the amount of heat produced in the reactions (1-4) can be measured. Safety Precautions Lab coats, goggles, and gloves were used in this lab to ensure safety. Procedure The insulating calorimeter was a Styrofoam cup with a thermometer and stirring rod. 75ml of 2M NaOH was placed in the cup and the temperature was recorded. 75ml of 2M HCl was added and completely stirred with the thermometer. The highest temperature was noted. The same procedure was repeated for reactions 2 and 3. The temperature change was found in order to calculate the heat absorbed. Further, the number of moles of the reacting acid and base were estimated and H/mole obtained for each neutralization reaction. For reaction 4, 150ml of water (50ËÅ ¡C) was transferred into an 8oz Styrofoam cup. After that, 25g of KNO3 was weighed out with its temperature assumed to be room temperature, ti. The water in the Styrofoam cup was stirred with a stirring bar and its temperature t2 was taken using the thermister. All the KNO3 was added and thoroughly stirred until it dissolved. Finally, the temperature of the system was recorded at intervals of 30 seconds until it was complete tf. Data and Results Table 1 shows the data consisting of the amounts of reactants used as in the procedure as well as the calculated results of the heat change and the heat change per mole. The temperature difference in table 1 is obtained using T= Tf -Ti. Calculations for Hrxn and H/mol of acid and H/mol of base are also done and indicated in the table. Further, the mass used was calculated from the product of water density (1.00g/cm3) and the volume of solution in each case. The specific heat capacity was taken to be that of pure water, which is 4.184J/g-deg. Table 1 Results Data Measured data Calculated data Acid Base Total volume (ml) Ti(ËÅ ¡C) Tf(ËÅ ¡C) T Hrxn(J) H/mol of acid (J/mol) H/mol of base (J/mol) HCl NaOH 150 34.5 35.4 0.9 -564.84 3765.6 3765.6 HNO3 NaOH 150 30.8 34.4 3.6 -2259.36 15062.4 15062.4 CH3CO2H NaOH 150 21.3 21.6 0.3 -188.28 1255.2 1255.2 Salt Water vol.(ml) Salt mass (g) Ti(ËÅ ¡C) Tf(ËÅ ¡C) Hsoln(J) H/mol (J/mol) KNO3 150 25 16.8 12.2 -4.6 2886.96 11673.92J/mol The temperature difference T= Tf -Ti For reaction 1, T= 35.4-34.5=0.9ËÅ ¡C. In the same manner, T for reactions 2-4 was obtained as 3.6ËÅ ¡C, 0.3ËÅ ¡C and -4.6ËÅ ¡C respectively. Calculations for Hrxn and H/mol Heat change = mCT qrxn = - qcalorimeter Cwater = 4.184 J/g ºC Hrxn= qrxn = mCT = (density of waterÃÆ'—volume) ÃÆ'— C of water ÃÆ'— T For reaction 1, q= (1ÃÆ'—150)ÃÆ'—4.184ÃÆ'—0.9= 564.84J However, qrxn = - q, which gives qrxn as -564.84J In the same way, qrxnfor reactions 2 and 3 were found as -2259.36J and -188.28J respectively. H/mol of acid (J/mol) Moles of acid = moles/literÃÆ'— vol. in liters For the neutralization reactions 1-3, moles of acid= 2ÃÆ'—75/1000= 0.15 mol, thus giving H/moles of acid for reaction 1 as -564.84J/0.15mol= 3765.6J/mol. In the same manner, moles for reactions 2 and 3 were found to be 15062.4J/mol and 1255.2J/mol respectively. H/mol of base (J/mol) Moles of base = moles/literÃÆ'— vol. in liters For the neutralization reactions (1-3) moles of base= 2ÃÆ'—75/1000= 0.15mol Giving H/moles of base for reaction (1) as -564.84J/0.15mol= 3765.6J/mol and in the same way for reactions (2) and (3) are 15062.4J/mol and 1255.2J/mol. For reaction 4 of KNO3, qrxn = mCT = (density of waterÃÆ'—volume) ÃÆ'— C of water ÃÆ'— T Therefore, q= (1ÃÆ'—150)ÃÆ'—4.184ÃÆ'—-4.6= -2886.96J hence qrxn=2886.96J H/mol =H /n =H / moles of KNO3 =H/ (mass/molar mass) =2886.96/(25/101.1032) =11673.92J/mol. Discussion and Conclusion This experiment approximated the specific heat values of reactants and salt solutions in the neutralization reactions to be equa...

Implicit and Explicit Communication Rules - 1925 Words

Implicit and Explicit Communication Rules (Reaction Paper Sample) Content: Implicit and Explicit Communication Rules Name Institution Introduction Rules, whether implicit or explicit, to large extent influence our interactions with other people and the environment we live in. As human beings, in order to coexist harmoniously with one another, we have to be aware of the norms, both written and unwritten, in our surrounding. How we perceive and respond to these rules vary. Some people may observe the rules devotedly while others may ignore them. Every event that involves a gathering of people has its rules that have to be observed by participants. This essay examines the implicit and explicit rules of Vancouver Art Gallery specifically at Picasso’s exhibit: The Artist and His Muses. ‘Picasso: The Artist and his Muses’ is arguably the most famous exhibit among those present at the Vancouver Art Gallery during the exhibition period. Picasso’s exhibit is among over 60 other works that include sculptures, paint ings, and works on paper that have been open for public viewing in the gallery since June 11 and will continue till October 2. After I got information about the exhibition from an article CBC News’ website authored by GalIager I was there to enjoy his artworks and also to gather information about communication rules. It was evident, however, that Picasso: The Artist and His Muses is not just a celebration of Picasso’s weeping or reclining, it is a celebration of the women he painted. One can’t help but think that the women were not simply muses; but were the inspiration behind the Picasso’s works. I observed that the exhibition was divided into six sections, one for each of the Picasso’s women. Each section had a big photograph of the woman and a story describing her. The fascination was clear among the visitors as they examined the pieces of art. Before the getting further into the exhibition I observed some explicit and implicit rules. The se cond explicit rule I noticed was the ‘DO NOT TOUCH’ sign. Despite it being an obvious rule in an art gallery, it was elaborated for everyone to see. This rule was followed fully, and despite having my eyes on people and how they behaved, I could not find any that got very close to the painting. Although there were many people in the exhibition, everyone kept their distance from the paintings. As such, this gives us another rule, an implicit one: that one is supposed to keep some space between him or her and the paintings. I did not see anyone breaking this implicit rule, and everyone kept a considerable distance away from the pieces of work. At the art gallery, Picasso’s exhibition starts with Fernande Olivier (1881-1966). Her story on the large photograph displayed shows that she was considered Picasso’s first great love. The story describing the painting show that Picasso and Olivier met in 1904 in Paris after the latter had run away from an abusive mar riage. The exhibition explains that Olivier had great influence on Picasso’s work. However, in 1912, due to mutual infidelities, they got separated. The section is clearly educational not only for me but also for the visitors in the exhibition. Through my observation, I gathered that the visitors took their time to examine each of the artworks by Picasso and they could not hide their amazements through occasional smiles and fascination written on their faces. It was at this point that I noticed other implicit rules: ‘maintain silence and keep your mobile phones away’. It was clear at the entrance that no photographs are allowed; however, it was until I was into the second section of Picasso’s exhibition that this implicit rule hit me. As a covert participant observer, I had decided to keep my phone off in order to concentrate on the rules and how other participants observed them. There were not any noises apart from participants asking the staff one or two things. Even this was done in low voices. I wrote down that two of the implicit rules observed by the participants in the gallery are keeping their voice down and keeping their phones on silent or vibration mode. This demonstrates the courteousness observed by the participants and how they respect other visitors and the staff of the gallery. Throughout the subsequent sections from Olga Khokhlova (1891-1955) to Jacqueline Roque (1927-1986), I noticed that people took their time to examine and read the story of each piece or art. Generally, throughout the Picasso’s exhibition, the explicit and implicit rules were observed as people took their time to enjoy the pieces of art. However, I noticed a young man using his phone and appeared to be taking photographs. I could not establish whether he was taking photos or not. As such, I cannot confidently say that he broke an explicit rule I mentioned earlier. It took me almost an hour to observe people in the Picasso’s exhib ition. As I had mentioned earlier, dwelling on Picasso’s exhibition was my main interest in the gallery. However, after gathering all I could in the exhibition, I decided to continue to other floors and see if I could gather anything important. I did not see any ‘NO SMOKING’ sign, but I did not notice anyone smoking. It was clear to me, therefore, that that was an implicit rule, and it was probably observed by everyone in attendance. In addition, another obvious rule and in the case of Vancouver, an implicit one, was that, ‘no food and drinks were allowed.’ I did not see anyone breaking this implicit rule; still I could not see a bottle of water in anyone’s possession. It is evident that the gallery has some explicit and implicit rules, all of which are generally observed by visitors. Analysis Throughout the one and a half our observation of rules in the gallery, I was able to get a picture of implicit and explicit rules present and how peop le respond to them. I will begin by analyzing the explicit rules I observed during my visit. As mentioned in the observation section, the first rule I noticed as I entered the gallery was an explicit one: ‘NO PHOTOS.' When such poster is displayed conspicuously, every visitor has to see it. In this regard, as one enters the gallery, one understands that it is prohibited to take photographs of the artworks. It is important to note that the reason for the prohibition of taking pictures is to protect the works of artists. Although I noted a young man appearing like he was taking a photograph, I was not close enough to determine whether or not he was actually doing it. Another explicit rule that I observed was the ‘DO NOT TOUCH’ sign on the exhibition. If the rule was not displayed conspicuously, it could have taken as an implicit one. However, this was displayed in the exhibition to be seen by the visitors as they examine the various pieces of art. As such, such rule means that the paintings can only be observed through eyes and not touching it. The reason for the prohibition of touching is clearly deducible: to prevent damage to the works of the artists and also to enable other people to view the paintings including future generations. These explicit rules were enforced by writing them and having them displayed to the visitors. From the observation and what I had written down, the implicit rules were pretty more that the explicit ones. One of the implicit rules I noticed was the distance kept from the paintings. People maintained a safe distance between them and the paintings despite it not being stated anywhere explicitly. This could be because they respected other people around and no one wanted to block others from viewing the Picasso’s paintings. Another rule I observed was calmness. The respect the visitor had for one another was clearly shown in...