The Heat Of Chemistry: An Analysis Of The Enthalpy Of Reaction
explanatory Essay
1440 words
1 Introduction The Heat of Reaction, also known and Enthalpy of Reaction is the change in the enthalpy of a chemical reaction that occurs at a constant pressure. It is a thermodynamic unit of measurement useful for calculating the amount of energy per mole either released or produced in a reaction. Since enthalpy is derived from pressure, volume, and internal energy, all of which are state functions, enthalpy is also a state function. As it is a form of energy, heat plays multiple important roles in chemical reactions The reaction heat of CL-20/HMX Cocrystal (Q) was determined at 293.15, 298.15, 303.15, 308.18 and 313.15K by using a DC-08 Calvet microcalorimeter to obtain fundamental thermodynamics parameters.
1 Experiment Section
1.2 Reagents: CL-20/HMX Cocrystal was prepared and purified in our laboratory (see
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In this essay, the author
- Explains that cl-20/hmx cocrystal was prepared and purified in our laboratory. n,n-dimethyl formamide (dmf) was used as solvent.
- Describes the experiments performed by a dc-08 calvet microcalorimeter. the temperature was held constant to within 0.01k during each measurement.
- Explains that the primitive values of heat effect of the polymerization of cl-20/hmx cocrystal were measured at different temperatures and each temperature was repeated four times. the results were obtained by dc-08 calvet microcalorimeter.
- Explains that equation (3.2) is applied to calculate the values of activation energy (e) and pre-exponential factor (a) by the slope and intercept of the linear equation.
- Explains that by substituting the values of t and mean ln(k) from table 2 into eq:3.3, the standard molar activation gibbs free energy at different temperatures is obtained.
- Explains that equation (3.4) is applied to calculate the values of the standard molar activation entropy and the standard molar
- Describes how the cl-20/hmx cocrystal sample was dissolved in dmf at 298.15 k to form solutions. the experimental and calculated values of enthalpy of dissolution are listed in table 1.
- Explains the empirical formula of enthalpy[15] _diss h(b=b) of dissolution in dmf and the value of the standard
- Explains the empirical formula of relative apparent molar enthalpy _diss h_apparent for cl-20/hmx cocrystal.
- Explains the empirical formula of the relative partial molar enthalpy for cl-20/hmx cocrystal.
- Explains the enthalpy of a chemical reaction that occurs at constant pressure. the reaction heat of cl-20/hmx cocrystal was determined at 293.15, 298.15, 303.15, 308.18 and 313.15k.
- Explains that h_ is the total enthalpy of a reaction, k the rate constant represented with conversaion, and n the reaction order and the conversation.
- Explains how the values of and are obtained by combining eqs.3.5 and 3.6 in table 3. table 3.4 shows the value of k and become big with temperature increase.
- Explains how the enthalpy of dissolution of cl-20/hmx cocrystal in n,n-dimethyl formamide (dmf) was measured by a dc08 calvet microcalorimeter at 298.15k.
- Describes how the dc08 calvet microcalorimeter operates at 298.150.001k. the reaction and reference cells are placed inside a metallic block of the calorimeter.
- Analyzes the empirical formula of enthalpy for the dissolution processes of cl-20/hmx cocrystal in dmf describing versus the b relation.
- Describes the kinetic dissolution of cl-20/hmx cocrystal in dmf using the eq.(4.10) and (4.11) as the models function describing the process.
- Explains that ht represents the enthalpy at time t, i: any time during the process, and h : the dissolution rate constant of cl-20/hmx cocrystal in dmf.
From Eq.(1), the empirical formula of enthalpy[15] ∆_diss H(b=b)of dissolution in DMF and the value of the standard enthalpy of dissolution ∆_diss H(b=0)
For CL-20/HMX Cocrystal are as follows:
∆_diss H=12.78509-1480.31579b+579.5614b^(1⁄2) (4.2)
And
∆_diss H_m^θ=12.78509 kJ 〖mol〗^(-1) (4.3)
According to the relationship as shown in Eq.(4.4):
∆_diss H_apparent=∆_diss H(b=b)-∆_diss H(b=0) (4.4)
From Eq.(4.1), the empirical formula of relative apparent molar enthalpy ∆_diss H_apparent for CL-20/HMX Cocrystal is obtained:
∆_diss H_apparent=-1480.31579b+579.5614b^(1⁄2) (4.5)
According to the empirical formula as presented in Eq(4.6):
∆_diss H_partial=b((∂∆_diss H)/∂b)+∆_diss H_apparent (4.6)
Form Eqs.(1) and (2), the following empirical formula of the relative partial molar enthalpy for CL-20/HMX Cocrystal is obtained:
∆_diss H_partial=-2960.63158b+869.3421b^(1⁄2) (4.7)
According to the empirical formula described in
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