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Determination of a Reaction's Activated Energy Using Naoh As A DOI: 10.26717/BJSTR.2018.06.001282 Anita Kovač Kralj. Biomed J Sci & Tech Res ISSN: 2574-1241 Research Article Open Access Determination of a Reaction’s Activated Energy Using Naoh as a Reactant Anita Kovač Kralj* Faculty of Chemistry and Chemical Engineering, University of Maribor, Slovenia Received: June 14, 2018; Published: June 21, 2018 *Corresponding author: Anita Kovač Kralj, Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, Maribor, Slovenia Abstract Determining chemical kinetics is the basis for reactor design, the determining of activated energy, energy efficiency, steam production, and integrating the reactor’s outlet stream with the inlet. The purpose of this article is to describe a sensitivity method for concentration and activated energy determination. This sensitivity method defines the sensitivity parameter for determining the characteristics of a reaction using strong electrolytes (for example sodium hydroxide - NaOH) as reactants. The sensitivity parameter is constant throughout this specific reaction. Concentrations of strong electrolytes can be determined by the sensitivity method, which is based on the measurement of conductivities. This method proposes continuous concentration determination of NaOH (or strong electrolyte) as a reactant or product. This sensitivity method wasKeywords: tested using titration. Sensitivity Method; Strong Electrolyte; Concentration; Activation Energy Introduction algorithms. Advances in computing have allowed researchers to The basis is presented for determining concentration and obtain increasing amounts of chemically-relevant information activated energies from the reactions of strong electrolytes. from their data; however, this is not always achieved using simple Determining these concentrations is basic for analytical chemistry, data-processing techniques. It is important to establish true using different methods. Eldridge, Piret [1] obtained the pseudo- mathematical models for utilization within the chemical industry first-order reaction rate constant using a batch reactor. In order [4]. to determine the acetic anhydride concentration, samples from the reactor were withdrawn into tarred flasks containing 15-20 Chemical kinetics, also known as reaction kinetics, is the times the quantity of saturated aniline-water required to react study of chemical processes’ rates. Chemical kinetics includes with the sample. Since the anhydride rapidly acetylates the aniline, investigations into how different experimental conditions can thus producing acetanilide and acetic acid, the samples were then influence the speed of a chemical reaction and yield information titrated to determine the concentration of acetic acid. In another about the reaction’s mechanism and transition states, as well as study, Shatyski and Hanesian [2] determined the kinetics of the the construction of mathematical models that can describe the above reaction by using temperature-time data obtained under characteristics of a chemical reaction. In 1864, Peter Waage and adiabatic conditions within a batch reactor. The use of in-situ FTIR Cato Guldberg pioneered the development of chemical kinetics by spectroscopy has already been demonstrated, when following the formulating the law of mass action, which states that the speed of hydrolysis of acetic anhydride reaction [3]. An analysis of the batch a chemical reaction is proportional to the quantity of the reacting reactor’s data showed that the hydrolysis of acetic anhydride is a substances [5]. The different forms of energy include kinetic, pseudo-first order reaction. The rate constants were calculated potential, thermal, gravitational, sound, elastic, and electromagnetic from the batch data using both integral and differential methods energy. These forms of energy are often named after a related force. of analysis. German physicist Hermann von Helmholtz established that all A forms of energy are equivalent-energy in one form can disappear Advances in electronics and computing over the past 30 but the same amount of energy will reappear in another form. years have revolutionized the analytical laboratory. Technological restatement of this idea is that energy is subject to a conservation developments have allowed instruments to become smaller, law over time [6]. This paper studies the concentration and activated faster, and cheaper, while continuing to increase accuracy, energy determined by the reactant NaOH (strong electrolytes), precision, and availability. Furthermore, software sold with many using the sensitivity method. commercial instruments contains automatic data-processing Cite this article: : . 4937 Anita Kovač Kralj. Determination of a Reaction’s Activated Energy Using Naoh as a Reactant. Biomed J Sci&Tech Res 6(1)- 2018. BJSTR. MS.ID.001282. DOI 10.26717/ BJSTR.2018.06.001282 Anita Kovač Kralj. Biomed J Sci & Tech Res Volume 6- Issue 1: 2018 The Sensitivity Method Λ = Λo − m m K c Λm (2.5) The sensitivity method is an alternative method for accurately 2 Where introduces the molar conductivity in Siemens metre- quantifying reactant or product concentrations during NaOH (strong −1 κ Λ = electrolytes) determination. This method applies a sensitivity squared per mole (S m molm ), which is defined as: c parameter for determining concentrations and activated energies c (2.6) for strong electrolytes (such as NaOH), by using conductivity. κ Specific characteristic-sensitivity parameter (s) can be found from Where is the molar concentration of the added−1 electrolyte, Λo c and is the conductivitym in siemens per metre (S m ). the measurements for strong electrolytes. Concentrations of strong o t) Λ electrolytes ( can be determined by using the sensitivity method. The constant is the limiting molar conductivity, the molarm This method proposes a continuous determination of reactant or s conductivity within the limit of zero concentration. The for product concentrations. Each reaction using NaOH as reactant has sodium o hydroxide at a temperature2 of around 25°C is2 [7]: Λ=m 5.01 + 19.91 = 24.92 the specific characteristic sensitivity parameter ( ), which can be −1 −1 mS m mol = 2492 mS dm mol (2.7) determined using the sensitivity method by applying conductivity. c κ0 Conductivity for a specific reaction has a specific characteristic, Kohlrausch’s constant can0 be calculated by known values for therefore certain sensitivity parameters can be determined -the the initial concentration ( ) and initial conductivity ( ), using sensitivity constant, which is constant during a specific reaction. equations 2.5 and 2.6: Λo κ K = m − 0 c 0.5 c 1.5 0 0 (2.8) The essence of the strong electrolytes theory is that you can determine the concentration of a reactant or product. The reaction can be observed by using the concentrationκ calculation. The two Λo − K c = basic equations 2.5 and 2.6m are used:c (2.9) The concentration is expressed by equation 2.9 for the numerical method: κ + c1.5K c = o Λm (2.10) Figure 1: The sensitivity method. The concentration can be calculated by using a numerical method (eq. 2.10; for example successive substitution; addition A). This sensitivity method is a very simple method for the The initial concentration (zc) and the allowed differences between determining concentrations cc=–· ∆ ofκ strong s electrolytes (Figure 1): t 00 the initial and target values (EPS) are needed. The determination of (2.1) cct =00–· ∆κ s any concentration change by using a numerical method is very long- cc= – (κκ–) · s (2.2) term, so it is only used at the beginning so that you can determine tt00 the sensitivity constant of the conductivity. The sensitivity method (2.3) was tested for various real reactions by using NaOH as reactant c t Case(chapter study 3) (Figure 1). The non-reactive reactant’s (such as NaOH),κ concentration depends on time ( ) which can be calculated by using equations 2.1 or 2.3 with a difference in conductivitys (Δ ; eq. 2.2). The sensitivity method was tested to synthesize sodium The sensitivity constant ( ) for a specific reaction can be methoxide, sodium benzoate, and sodium acetate. Sodium calculated by equations= ( cc2.4:00 − tt) /–(κκ) hydroxide (NaOH) was, in all cases, the reactant and a strong Sodium Methoxide Synthesis κ electrolyte. c0 0 (2.4) is the known initial reactant’s concentration and is the 3 known initial conductivity of strong electrolytest (NaOH). We need Sodium methoxide (CH ONa) was produced from sodium c only a fewt measurements of conductivity κ , depending on time, hydroxideNaOH (NaOH) + CH and OH methanol = H O ++ Na(MeOH)+− CH in O a batch reactor: s 32 3 so that can be calculated using the Kohlrausch law (equations (R1) 2.5; [7]). The constant is equal for all measurements. Friedrich Kohlrausch showed that, at low concentrations, the molar A B C conductivities of strong electrolytes vary linearly with the square The main application of sodium methoxide today is its use root of the concentration: as a catalyst in the production of bio-diesel. During this process, Biomedical Journal of Scientific & Technical Research (BJSTR) 4938 Anita Kovač Kralj. Biomed J Sci & Tech Res Volume 6- Issue 1: 2018 Table 1: Experimental data and calculation for sodium methoxide synthesis, using numerical and sensitivity methods. vegetable oils or animal fats, which are chemically fatty acid triglycerides, are transesterified with methanol to produce fatty cA /(mol/L) cA /(mol/L) acida) methyl Determining esters (FAMEs). the concentration using the sensitivity t/min κ/(mS/dm) calculated by calculated by num. meth. sens. meth. method: 0.00 A schematic diagram of the laboratory apparatus is 0.80 247.0240.0 0.1670 shown in (Figure 2). A batch reactor with a stirrer was used in 0.91 0.1599 0.1599 the experiment. Methanol (0.12mL) was heated into a reactor at a temperature of 28 °C, and 3.34g pure NaOH was dissolved 238.0 0.1578 κt t 2.00 in 500mL of water. Both substances were mixed and the 1.25 236.7 0.1565 0.1565 κ0 conductivity ( ) was measured depending on time, (Table 234.1 0.1539 cA0, 1). The first conductivity of the sodium hydroxide ( ) was 2.25 233.5 0.1532 0.1532 247mS/dm.
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