Liquid ethanol

The vapor pressure of ethanol at 25°C is 58.9 Torr. A sample of ethanol vapor at 25°C and 58.9 Torr partial pressure is in equilibrium with a very small amount of liquid ethanol in a 10.0-L container also containing dry air, at a total pressure of 750.0 Torr. The volume of the container is then reduced at constant temperature to 5.0 1,. (a) What is the partial pressure of ethanol in the smaller volume Explain your reasoning. 

Design a shell and tube exchanger to heat 50,000 kg/h of liquid ethanol from 20°C to 80°C. Steam at 1.5 bar is available for heating. Assign the ethanol to the tube-side. The total pressure drop must not exceed 0.7 bar for the alcohol stream. Plant practice requires the use of carbon steel tubes, 25 mm inside diameter, 29 mm outside diameter, 4 m long. 

Table 6.4 gives the radiation yields of stabilized electrons in some selected glasses at 77 K with about 15% uncertainty. A detailed discussion of these yields has been given by Kevan (1974). Hase et al. (1972a) observed et spectrum in ethanol at 4 K with a peak at 1500 nm on quick warming to 77 K, the spectrum relaxed with the same peak in the visible as that of es in liquid ethanol. Hase et al. (1972b) also observed et spectrum at 4 K in 3MP with no clear maximum. On quick warming to 77 K, the spectrum relaxed with a clear maximum at -1700 nm. 

We have already illustrated equation 2.32 for a solution enthalpy (of liquid ethanol see section 2.5). We now apply it to another phase transition the vaporization of a pure substance. 

The pressure effect on the enthalpy of liquid ethanol can be estimated from equation 2.15, now written in terms of the coefficient of thermal expansion, a ... 

In the second configuration (moderate swirl) tested (see Fig. 20.2a), only the air stream was forced and no liquid-fuel pulsations were imposed. The experiments were performed with a Parker-Hannifan Research Simplex Atomizer. The atomizing nozzle consisted of a primary liquid ethanol feed with a coaxial primary air stream. The air stream passed through a set honeycomb, flow-straightener, and swirl vanes to provide the necessary level of swirl. Three loudspeakers were used to excite the primary air. 

Fig. 8. Dependence of the 2974-cm band of liquid ethanol on the number of catalyst coatings on an IRE. Intensities were normalized with respect to the ethanol signal measured on the uncoated Ge IRE (47).

R. Ludwig, F. Weinhold, and T. C. Farrar. Quantum cluster equilibrium theory of liquids molecular clusters and thermodynamics of liquid ethanol. Mol. Phys. 97, 465-77 (1999). 

Hence B0 i is lowest for the OH proton in pure ethanol. (See Fig. 8.2.) A sweep from low to high B0 at fixed rf frequency corresponds to a sweep from high to low rf frequency at fixed B0. Figure 8.2 shows the NMR spectrum of pure liquid ethanol. (With better resolution than in this figure, the spectrum shows a fine structure due to spin-spin coupling see Section... 

In 1951 Arnold, Dharmatti, and Packard observed the proton NMR spectrum of liquid ethanol to consist of three lines the separation between these lines was found to increase linearly with increasing applied field B0. The three lines are attributed to the three chemically different protons in CH3CH2OH. NMR studies where conditions are such as to resolve lines due to identical nuclei in chemically different environments are given the adjective high-resolution. Let us consider why the chemical environment of a nucleus affects its NMR transition frequency. 

Because water has the higher boiling point of the two, it condenses out from the mixture with ethanol. This is what takes place in the fractionating column. The water condenses and drips back into the flask while the ethanol vapour moves up the column and into the condenser, where it condenses into liquid ethanol and is collected in the receiving flask as the distillate. When all the ethanol has distilled over, the temperature reading on the thermometer rises... 

Saiz L, Padro JA, Guardia E. 1997.Structure and dyanmics of liquid ethanol. J Phys ChemB 101 78-86. 

Dipole-dipole attractions also contribute to the relatively high boiling points of alcohols and ethers. The polarized C—O and H—O bonds and the nonbonding electrons add to produce a dipole moment of 1.69 D in ethanol, compared with a dipole moment of only 0.08 D in propane. In liquid ethanol, the positive and negative ends of these dipoles align to produce attractive interactions. 

A clear, colourless, mobile, volatile, readily inflammable, hygroscopic liquid. Ethanol (96%) boils at about 78°. 

An unbalanced chemical equation is of limited use. Whenever you see an equation, you should ask yourself whether it is balanced. The principle that lies at the heart of the balancing process is that atoms are conserved in a chemical reaction. The same number of each type of atom must be found among the reactants and products. Also, remember that the identities of the reactants and products of a reaction are determined by experimental observation. For example, when liquid ethanol is burned in the presence of sufficient oxygen gas, the products will always be carbon dioxide and water. When the equation for this reaction is balanced, the identities of the reactants and products must not be changed. The formulas of the compounds must never be changed when balancing a chemical equation. That is, the subscripts in a formula cannot be changed, nor can atoms be added or subtracted from a formula. 

Ethanol (C2H5OH) has been proposed as an alternative fuel. Calculate the standard enthalpy of combustion per gram of liquid ethanol. 

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. 

Table B.l lists standard heats of combustion for a number of substances. The given values are based on the following assumptions (a) all carbon in the fuel forms COT(g), (b) all hydrogen forms H20(l), (c) all sulfur forms S02(g), and (d) all nitrogen forms N2(g). The standard heat of combustion of liquid ethanol, for example, is given in Table B.l as AH° = -1366.9 kJ/mol, which signifies...

The liquid ethanol exits the process at 298.15 K (25°C). Wliat is the heat transfer associated with this overall process per mole of ethanol produced ... 

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