Heat capacity of ethanol

A sample of ethanol, C2H5OH, absorbs 23.4 kj of energy. The temperature of the sample increases from 5.6°C to 19.8°C. What is the mass of the ethanol sample The specific heat capacity of ethanol is 2.46 J/g °C. 

The heat capacities of ethanol vapor and hydrogen are given in Table B.2. For acetaldehyde vapor, the heat capacity is given by Reid, Prausnitz, and PoUng. ... 

Equations 2.39 and 2.40 lead to Avap//°(C2l I5OH) = 42.4 0.5 kJ mol-1 [40], which agrees with the mean of the calorimetric results for the same liquid, 42.30 0.04 kJ mol-1 [39]. Note that the less sophisticated approach (equation 2.33) apparently underestimates the vaporization enthalpy by 0.6 kJ mol-1. However, this is not true because AvapH = 41.8 kJ mol-1 refers to the mean temperature, 326 K. A temperature correction is possible in this case, because the molar heat capacities of liquid and gaseous ethanol are available as a function of T [40]. That correction can be obtained as ... 

Aminomethylpyridine (picolylamine) is an important ligand in respect to spin cross-over, [Fe(2-pic)3]Cl2 being the key compound." Fleat capacity measurements on [Fe(2-pic)3]Cl2 EtOH gave values of 6.14kJmol and 50.59 JK moC for the spin eross-over entropy the determined entropy was analyzed into a spin contribution of 13.38, an ethanol orientational effeet of 8.97, and a vibrational contribution of 28.24 JK mol. " This compound exhibits weak cooperativity in the solid state." The heat capacity of [Fe(2-pic)3]Cl2 MeOH is consistent with very weak cooperativity." [Fe(2-pic)3]Br2 EtOH shows a lattice expansion significantly different from that expected in comparison with earlier-established behavior of [Fe(2-pic)3]Cl2 EtOH." ... 

Figure 1 Apparent molar volumes and heat capacities of sodium deca noate In water (ref. 11) and In 0.05 mol kg of 2-butoxy-ethanol at 25°C.

The heat capacity of liquid water is 1 cal/(g-°C). and that of ethanol is 0.54 cal (g- O. Estimate the heat capacity of a mixture containing 50% ethanol and 50 i water by mass. 

Table B.2 lists values of the heat capacity of liquid ethanol at two temperatures. Use the tabulated values to derive a linear expression for Cp T) then use the derived expression and data in Table B.l CO calculate the heat transfer rate (kW) required to bring a stream of liquid ethan ol flowing at 55.0 L/s from 20 C to the boiling point at 1 atm. 

The amount of heat given off by the system (in the sealed compartment) raises the temperature of the calorimeter and its water. The amount of heat absorbed by the water can be calculated using the specific heat of water similarly, we use the heat capacity of the calorimeter to find the amount of heat absorbed by the calorimeter. The sum of these two amounts of heat is the total amount of heat released by the combustion of 1.000 gram of ethanol. We must then scale that result to correspond to one mole of ethanol. 

A Ho(PDC)3(o-phen) complex has been obtained and studied by Xie et al. [184] from the reaction of hydrated holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen-H20) in absolute ethanol. The enthalpy of complex formation from a solution of the reagents and the molar heat capacity of fre complex were determined by using a heat conduction microcalorimeter. The enthalpy of complex formation from the reaction of the reagents in the solid phase, was calculated on the basis of an appropriate thermochemical cycle and other auxiliary thermodynamic data. The thermodynamics of formation of the complex were investigated by the reaction in solution at the temperature range of 292.15 - 301.15 K. The constant-volume combustion energy of the complex, Act/, was also determined. 

Calculate the excess constant-pressure heat capacity and the actual constant-pressure of a solution of ethanol in water at 323 K that contains 20% ethanol by mol and use this result to obtain the constant pressure heat capacity of the solution. 

Additional data. The ideal-gas heat capacities of the pure species in this reaction are ethanol 118 J/mole K acetaldehyde 90 J/mole K hydrogen 30 J/mole K. 

Figure 2.20 Representation of the liquid heat capacities of -pentane (a) and ethanol (b) with the VTPR equation after simultaneous fitting to vapor pressure and heal capacity data. Experimental data from [9).

The partial molar heat capacity of gases is usually larger in water than in other solvents. This quantity is obtained from the second derivative of experimental curves and therefore is generally not very accurate. Nevertheless, the difference between water and other solvents is considered to be quite clear-cut. As an example, the partial molar heat capacity of argon in water at room temperature is about 50 cal/mole deg, whereas in ethanol, methanol, or p-dioxane, it is almost zero. Table 7.2 includes some information on the partial molar heat capacity of methane in water and in nonaqueous solvents. 

Conti, G. Gianni, P. Matteoli, E. Excess enthalpies and excess heat capacities of the ternary system ethanol -t tetrahydrofuran +... 

Find AH for the combustion of ethanol (C2HgO) to carbon dioxide and liquid water from the following data. The heat capacity of the bomb calorimeter is 34.65 kJ/K and the combustion of 1.765 g of ethanol raises the temperature of the calorimeter from 294.33 K to 295.84 K. 

Practice Problem B A 25.95-g sample of methanol at 35.6°C is added to a 38.65-g sample of ethanol at 24.7°C in a constant-pressure calorimeter. If the final temperature of the combined liquids is 28.5°C and the heat capacity of the calorimeter is 19.3 J/°C, determine the specific heat of methanol. 

The density of ethanol at 20 °C is 0.789 g/cm3, and its heat capacity is 2.85 J/g °K. These properties may be assumed to be constant over the temperature range of interest. The solution is so dilute that one may assume that its property values are essentially equal to those of pure ethanol. Batch reactor operation is assumed. 

B. 1,4-Cyclohexanedione. The purified 2,5-dicarbethoxy-l,4-cyclohexanedione (170 g., 0.66 mole) (Note 5) and 170 ml. of water are placed in a glass liner (vented) of a steel pressure vessel of 1.5-1. capacity (fitted with a pressure-release valve). The vessel is sealed, heated as rapidly as possible to 185-195°, and kept at this temperature for 10-15 minutes (Note 6). The reaction vessel is immediately removed from the heater, placed in a large tub of ice water, and cooled to room temperature. The gas pressure then is carefully released. The resulting yellow to orange liquid is transferred to a distillation flask with the aid of a minimum volume of ethanol, and most of the water and ethanol is removed under reduced pressure by means of a rotary evaporator. The flask is attached to a short heated column fitted with a short air condenser. The remainder of the water and ethanol is removed under reduced pressure, and the 1,4-cyclohexanedione is distilled, b.p, 130-133° (20 mm.). The product solidifies to a white to pale-yellow solid, m.p. 77-79°, deld 60-66 g. (81-89% yield from 2,5-dicarbethoxy-l,4-cyclohexanedione). The compound may be conveniently recrystallized from carbon tetrachloride (7 ml. per gram of dione) the purified product is obtained as white plates, m.p. 77-79° (90% recovery). 

Tanaka. R. and Toyama, S. Excess molar volumes and excess molar heat capacities for binary mixtures of ethanol with chlorocyclohexane, 1-nitropropane, dibutyl ether, and ethyl acetate at the temperature of 298.15 K. 7 Chem. Eng. Data, 41(6) 1455-1458,1996. 

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