Heat boiling

A student is asked to calculate the amount of heat involved in changing 10.0 g of liquid bromine at room temperature (22.5°C) to vapor at 59.0°C. To do this, one must use Tables 8.1 and 8.2 for information on the specific heat, boiling point, and heat of vaporization of bromine. In addition, the following step-wise process must be followed. 

When the furnace is fully heated, boiling water is placed beneath the round-bottom flask and cold water passed through the condenser. Acetone is now dropped in at the rate of 3-4 cc. per minute. About half the acetone should be recovered as distillate in cylinder B (Note 5). Ketene, admixed with methane, carbon monoxide, and ethylene, passes into the reaction flasks (Note 6) in 25-20 per cent yields. The flow may be interrupted at will by checking the acetone flow. 

Ruthenium silicide is a very hard, white substance, of great stability. It volatilises in the electric arc. Chlorine slowly attacks it, fluorine readily. It burns in oxygen at high temperatures, and is decomposed by sulphur vapour at red heat. Boiling acids do not affect it. 

Microburners are also useful for heating boiling tubes and test tubes, sealing the ends of melting point tubes (see p. 88), making micropipettes for chromatography (see p. 217) and bending the ends of Pasteur pipettes for special purposes (see p. 112). 

Steam distillation. If two liquids are nearly insoluble in each other, neither one lowers the vapor pressure of the other therefore the total vapor pressure of a mixture of these two liquids will be the sum of their vapor pressures. If the mixture is heated, boiling begins when the combined vapor pressure of the two immiscible components equals the pressure of the atmosphere. The vapor and hence the distillate contain both components in the ratio of their vapor pressures. If, for example, at the temperature of the distillation 95 per cent of the vapor pressure is due to component A (of a mixture A and B), then the composition of the distillate will be 95 mole per cent A and 5 mole per cent B. This principle is applied in the separation of organic compounds from a mixture, at temperatures which are far below their boiling point, by distillation with steam. Consider, for example, a mixture of aniline, which boils at 184°, and water. At 100° the vapor pressure of aniline is 45 mm and that of water 760 mm at 98° the vapor pressure of water is 727 mm and that of aniline 40 mm. Therefore the combined vapor pressure of a mixture of water and aniline at 100° is 805 mm, and at 98°, 767 mm. It is evident that near 98° the total vapor pressure will be one atmosphere and the mixture will boil., The distillate will contain water and aniline in the mole ratio of their partial pressure. The process is called steam distillation and is further discussed in Experiment 27 (page 163). 

Properties Reddish-brown, fuming liquid pungent chlorine odor. D 1.638 (15.5C), fp—78C, bp decomposes above 59C on rapid heating, boils near 60C, refr index 1.567 (20C). Decomposes in water and alcohol soluble in benzene. 

K (thermal conductivity) Cp (specific heat) Boiling point elevation 3. Evaporation Rate... 

Multiuse including heating, boiling, reactions. Related topics are distillation (Section 16.11.4.2) and reactors (Section 16.11.6.4). 

Mercury (10" torr) or a low vapor pressure oil (Myvoil, 10 torr Octoil, lO torr) is used as the liquid. This liquid is heated, boils up the left side (Figure 7-11) and comes down the right side. 

Directions In order to avoid mistaking for hydrogen the dissolved air liberated when the water used in the experiment is heated, boil in a beaker for about 1 minute about 250 c.c. of water. Pour about 10 c.c. of the boiled water into each of six test tubes and put them in the hot water in the beaker... 

Vapor formation rates in rapidly heated systems have been measured by Faneuff, McLean, and Scherrer (FI) and Cole (C4) for wires in a stationary liquid pool, and by Johnson et al. (Jl, J2, Tl) for a metal ribbon suspended in a channel flow. Void growth rates in a volume-heated boiling system were studied by Lipkis, Liu, and Zuber (L8). In practice the total vapor volume... 

Microwave (boiling toluene) Conventional heating (boiling toluene) Room temperature (tolitene)... 

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