Naphthalene liquid phase

The naphthalene wUl dissolve in the liquid a-naphthol and, according to Raoult s law, the vapour pressure of the latter will be reduced. Hence a-naphthol will pass preferentially into the liquid phase and, if the external temperature is maintained at 95 5°, the ultimate result will be the complete melting of the solid a-naphthol since melting requires heat and no heat is imparted to the system, the temperature will fall. 

E8.12 The melting point of 1,4-dichlorobenzene is 326.4 K and that of naphthalene is 353.4 K. The eutectic point occurs at a temperature of 303.4 K and a mole fraction of naphthalene in the liquid phase of 0.394. Assume ideal liquid solutions, no solid solubility, and ArusCp.m = 0 and calculate AfusHm for 1,4-dichlorobenzene. 

Fusion and vaporization are the most familiar phase changes, but sublimation is also common. Sublimation is a phase change in which a solid converts directly to a vapor without passing through the liquid phase. Dry ice (solid CO2) sublimes at 195 K with A ii/subl — 25.2 kJ/mol. Mothballs contain naphthalene (Cio Hg,... 

Analysis Techniques. The contents of the major breakdown products of xetralin (naphthalene and 1-methyl indan) present in the distillate were determined by gas-liquid chromatography using a Hewlett Packard Series 5750 Research Chromatograph with a 62m x 0.5mm diameter glass capillary SCOT column coated with nonpolar SE 30 liquid phase (see Reference (4 ) for details). 

Note that P is the pressure which pure chemical will exert in the liquid state, at the system temperature. For liquids such as benzene, this can be assumed to be the measurable liquid phase vapor pressure. In two situations, P becomes experimentally inaccessible. When the pure chemical is a solid, for example naphthalene with a melting point of 80°C, the only measurable vapor pressure at 25°C is that of the solid P , which is lower than that of the hypothetical liquid state. The ratio of the solid to liquid state vapor pressures can be estimated from... 

Our NMR technique for the determination of the solid-1iq-uid-gas phase line that ends at the UCEP again makes use of the fact that the NMR signal from nuclei with different relaxation rates can be easily separated. In this case we are distinguishing between the signal from the naphthalene-rich liquid phase formed when the S-L-G line is crossed and solid naphthalene. 

Since the spin-spin relaxation of the liquid phase naphthalene protons is much longer than that of the solid naphthalene protons, by once more using the spin-echo sequence with x =. 007 s we are able to monitor the NMR signal from the liquid phase only. 

The technique was implemented as follows. With solid naphthalene in our solubility cell we brought the system to a desired temperature and C02 pressure such that solid-supercritical gas equilibrium existed. The temperature was then slowly increased (heating rate approximately 1°C/hour) at constant pressure, while the NMR signal was monitored. When the S-L-G line was intersected, the solid naphthalene in the cell would melt with the formation of the naphthalene-rich liquid phase, and this resulted in a large and rapid increase in our NMR signal. The temperature at which we saw this discontinuous jump in our NMR signal gave the location of the phase line at that pressure. 

In a constant-volume bomb calorimeter with a heat capacity of 13.418 kJ/K, 1.17 g of naphthalene, C10H8, is burned. Fifty-two joules of energy are required to ignite the sample. If the temperature rise of the calorimeter is 3.318 K, what is the A U and AH of combustion of naphthalene What is the AHy of naphthalene (You may assume that all water is formed in the liquid phase.)... 

Mass Transfer Rate. The molar flux, NA = /cl(( cioiis — cc10h8 ), assuming the concentration of naphthalene in the bulk of the liquid phase is negligible, i.e. cc10hSl = 0, becomes... 

Moreau et al.56 obtained unexpected results in the alkylation of naphtalene with 2-propanol over H-Beta in the liquid phase at 200°C. Here a cyclic compound 1 was formed with a selectivity around 40% at 28.5% conversion. When applying HY as the catalyst alkylation to di- and trialkylnaphthalenes was faster but the cyclic compound was not observed. These results illustrate the more confined space within the zeolites Beta channels. The cyclic compound is assumed to be formed through iso-propylation of naphthalene followed by a hydride abstraction giving a carbenium ion, reaction with a propylene and finally ring-closure. 

E Dry ice (solid carbon dioxide), iodine crystals, and naphthalene (mothballs) all sublime and change from solid to gas phase without any apparent liquid phase. 

Why is it that when you buy ice cream from a vendor in a park on a hot summer day, the ice cream wrapper is not soaked with water from the ice that is used to keep it cold Is the vendor using ice at all Dry ice is the term for solid carbon dioxide. Dry ice can change from the solid phase right to a gas phase, without any apparent liquid phase in between. This process is called sublimation. Some other substances that can sublime are mothballs (naphthalene) and solid iodine. Deposition can be thought of being the opposite of sublimation. In this process a gas will form a solid, again without any apparent liquid phase in between. 

The manufacture of phthalic anhydride (world installed capacity ca. 4.4 Mt/a) has several points of similarity to that of maleic anhydride in that there are two alternative feedstocks and a large amount of heat is released. The first process, introduced by BASF at the end of 19 century, was based on the liquid phase oxidation of naphthalene catalyzed by mercury salts. It was later replaced by the cleaner gas phase process, carried out over vanadium and molybdenum oxides. Naphthalene was supplied by coal tar distillation and was used exclusively until the end of 1950s when u-xylene, of petrochemical origin, became an abundantly available feedstock (Equation 36). A few production units however can use either feedstock, taking advantage of price fluctuations in coke plants (naphthalene) and in refineries (u-xylene). 

Higher-molecular-weight amines are treated in the liquid phase usually in solvents like ethyl acetate, toluene, chlorobenzene, or chloro-naphthalene. This process is illustrated by the preparation of p-nitro-phenyl isocyanate (95%). Amine hydrochlorides or carbamic acids are sometimes used in place of the free amine. ... 

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