Enthalpy diagram methane

Figure B-15. Methane Hessure enthalpy diagram. (From Edmister and Lee, Applied Hydrocarbon Thetmodynamics. Vol. Second Edition, Gulf Publishing Company, Houston, TX, 1984.)...

Fig. 3. Enthalpy diagram (Aif298, kcal/mol B3LYP level of DFT) for reductive elimination of methane from one isomer of (R3P)2Cl2PtCH3(H), PR3=P(CH3)3 or PH3. The dotted line refers to the P(CH3)3 system, where the relative order of barrier heights changes in comparison to the PH3 system. The diagram was drawn using the data from Refs. (132,133).

Given in the literature are vapor pressure data for acetaldehyde and its aqueous solutions (1—3) vapor—liquid equilibria data for acetaldehyde—ethylene oxide [75-21-8] (1), acetaldehyde—methanol [67-56-1] (4), sulfur dioxide [7446-09-5]— acetaldehyde—water (5), acetaldehyde—water—methanol (6) the azeotropes of acetaldehyde—butane [106-97-8] and acetaldehyde—ethyl ether (7) solubility data for acetaldehyde—water—methane [74-82-8] (8), acetaldehyde—methane (9) densities and refractive indexes of acetaldehyde for temperatures 0—20°C (2) compressibility and viscosity at high pressure (10) thermodynamic data (11—13) pressure—enthalpy diagram for acetaldehyde (14) specific gravities of acetaldehyde—paraldehyde and acetaldehyde—acetaldol mixtures at 20/20°C vs composition (7) boiling point vs composition of acetaldehyde—water at 101.3 kPa (1 atm) and integral heat of solution of acetaldehyde in water at 11°C (7). 

Figare 6.5 Pressure/enthalpy diagram for methane. (Reproduced by permission of the Sheli Development Conj pany, Ct iyri0ht 194, P jbsh by C. ... 

Figure 3.3-2 Pressure-enthalpy diagram for methane. Source W. C. Reynolds, Tlieniwdv-namic Properties in SI, Department of Mechanical Engineering, Stanford University, Stanford, CA, 1979. Used with permi.ssion.) (This figure appears as an Adobe PDF file on the CD-ROM accompanying this book, and may be enlarged and printed for easier reading and for use in solving problems.)...

Figure 6.6 Enthalpy diagrams for exothermic and endothermic processes. A, Methane burns with a decrease in enthalpy because heat leaves the system. Therefore, Hf,nsi < Hinitiai, and the process is exothermic AH < 0. B, Ice melts with an increase in enthalpy because heat enters the system. Therefore, Hfinai > Hinisai. and the process is endothermic AH > 0.

Write a balanced equation and draw an approximate enthalpy diagram for each of the following (a) the combustion of 1 mol of methane in oxygen (b) the freezing of liquid water. 

Figure 9.11 I Enthalpy diagram for the combustion of methane. Here we imagine that one mole of CH4 is first converted to CO (step 1) and that the CO then reacts further to form CO2 (step 2). If we know the values of AHi and AHj, we can use them to calculate A-ffcomb ...

Buhner, K., Maurer, G. Bender, E. (1981). Pressure-enthalpy diagrams for methane, ethane, propane, ethylene and propylene. Cryogenics, 21,157-164. 

Figure 9 provides a comparison of the predictions of empirical methods with Wormald s data for a 50/50 mole percent mixture of steam and methane. As can be seen, the frequently used artifices of calculating mixture enthalpies by blending the pure component enthalpies at either total or partial pressures are very inaccurate. Likewise, the assumption of ideal gas enthalpy for the real gas mixture, equivalent to a zero enthalpy departure on the diagram, is an equally poor method. 

Fig. 5.28 The principle behind the ab initio calculation of heat of formation (enthalpy of formation) using an isodesmic reaction. Methanol and hydrogen are (conceptually) made from methane and water (other isodesmic reactions could be used) the 0 K enthalpy input for this is the ab initio energy difference between the products and reactants. Graphite, hydrogen and oxygen are converted into methane and water and into methanol and hydrogen, with input of the appropriate heats of formation. The heat of formation of methanol at 0 K follows from equating the heat of formation of methanol with the sum of the energy inputs for the other two processes. The diagram is not meant to imply that methanol necessarily lies above its elements in enthalpy...

The evaluation of the irreversible entropy production is very easily performed in these enthalpy, entropy diagrams as was shown by Knoche (A). It is simply for one mole methane ... 

The difference to the copper process is, that the reduction of nickel oxide with methane is an endothermic process, thus a heat engine could be employed. Figures 9 and 10 show the enthalpy, entropy diagrams of the reactions outlined in equations (8) and (9). (A metallurgist will not favor the reoxidation of nickel since it is very difficult, but equilibrium thernodynamic considerations do allow it.)... 

Figure 9. Enthalpy, entropy diagram of nickel oxide reduction with methane.

Enthalpy-temperature diagram for the complete combustion of methane with air. 

Substances considered in a compilation of the thermodynamic properties of refrigerants include hydrogen, parahydrogen, helium, neon, nitrogen, air, oxygen, argon, carbon dioxide, hydrocarbons (e.g. methane, ethane, propane, butane, isobutane, ethylene, and propene), and fluoro-and fluoro-chloro-hydrocarbons. Properties listed include those for the liquid and saturated vapour, superheated vapour, and unsaturated vapour. In addition, pressure-enthalpy, and in some instances pressure-entropy, diagrams are provided. 

Figure 5.31 Enthalpy level diagram for an exothermic reaction - the combustion of methane... 

Bagno (1998) presented a diagram (reproduced as Fig. 5.15) showing clearly that in all solvents examined, the enthalpy and entropy of solvation of methane are both negative and that at ordinary temperatures the TAS term is substantially larger than the AH term (so the solubility may be described as entropy dominated ). In the... 

For certain molecules, enthalpies of formation can be determined from combustion data. Using the diagram below, calculate the enthalpy of formation (AH), of methane gas CH4(g), and the enthalpies for two of the combustion reactions listed below. 

For an exothermic reaction, energy is released to the surroundings. So the enthalpy of the reactants must be greater than the enthalpy of the products. We can see from the enthalpy profile diagram for the combustion of methane (Figure 6.3) that - H eactants negative. 

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