Beaker scale

In order to obtain a-form crystal preferentially semi-batch cooling crystallization at low temperature below 284K Is considered more preferable as Investigated above sections. Authors studied the process In the beaker scale test and In the commercial operation. 

Generally, alkoxide-derived monodisperse oxide particles have been produced by batch processes on a beaker scale. However, on an industrial scale, the batch process is not suitable. Therefore, a continuous process is required for mass production. The stirred tank reactors (46) used in industrial process usually lead to the formation of spherical, oxide powders with a broad particle size distribution, because the residence time distribution in reactor is broad. It is necessary to design a novel apparatus for a continuous production system of monodispersed, spherical oxide particles. So far, the continuous production system of monodisperse particles by the forced hydrolysis... 

After the initial problems were solved, samples of 100% cotton knit fabric were dyed on a beaker scale five times from the same single-dye impregnation and fixation bath. The color differences between the fabrics and the initial dyeing (chosen as the standard) were within the desire two to four MacAdam unit range (Table XXVII). 

Following the laboratory- or beaker-scale experimentation when the students are satisfied as to feasibility of the preparation and have enabled themselves to acquire sufficient information to undertake a large-batch operation (5 to 10 lb), a small-scale-process laboratory study should then be undertaken. Attention should be paid to the engineering considerations involved in the production of the commodity. In order to obtain engineering data essential for the pilot plant investigation of the commodity selected, the following considerations may be important ... 

If the thermometer is to be used to determine the elevation of the boiling-point of a liquid on the addition of a solute, it must be remembered that at the boiling-point of the pure solvent the mercury must now be about 1-2 above the bottom of the scale S, and hence for adjustment purposes the temperature of the beaker of water should be 6—7 above the boiling-point of the liquid itself, instead of 1-2 as before. 

Sodium Hypochi ite. zM- This may be prepared with sufficient accuracy by dissolving 100 g. of NaOH in 200 ml. of water in a large beaker, cooling the solution, and then adding about 500 g. of crushed ice. Now counterpoise the beaker on a rough set of scales, and pass in chlorine from a cylinder until an increase in weight of 72 g. is obtained. Make up the solution to i litre and stir well. The solution must be kept in a cool dark place, but even then slowly decomposes. 

For preparations on a larger scale, mechanical stirring is recommended a beaker or bolt-head fla.sk should be used. 

These kinds of stores carry hobby/craft supplies, gimmicky science fair projects, ant farms and a low assortment of basic scienceware products such as beakers, thermometers, scales, rubber stoppers and most of the basic chemicals such as acids, bases and solvents. These places are listed in the chemicals section of any big city s yellow pages and are relatively safe places to get most of the basic lab necessities. The drawback is that they are really expensive and don t sell very large quantities of any chemical. It is possible to have these places special order a needed chemical as long as it s not a controlled chemical. 

The scale-up of filtration centrifuges is usually done on an area basis, based on small-scale tests. Buchner funnel-type tests are not of much value here because the driving force for filtration is not only due to the static head but also due to the centrifugal forces on the Hquid in the cake. A test procedure has been described with a specially designed filter beaker to measure the intrinsic permeabiHty of the cake (7). The best test is, of course, with a small-scale model, using the actual suspension. Many manufacturers offer small laboratory models for such tests. The scale-up is most reHable if the basket diameter does not increase by a factor of more than 2.5 from the small scale. 

Tank Cells. A direct extension of laboratory beaker cells is represented in the use of plate electrodes immersed into a lined, rectangular tank, which may be fitted with a cover for gas collection or vapor control. The tank cell, which is usually undivided, is used in batch or semibatch operations. The tank cell has the attraction of being both simple to design and usually inexpensive. However, it is not the most suitable for large-scale operation or where forced convection is needed. Rotating cylinders or rotating disks have been used to overcome mass-transfer problems in tank cells. An example for electroorganic synthesis is available (46). 

Procedure. Pipette 25.0 mL of the thiosulphate solution into the titration cell e.g. a 150mL Pyrex beaker. Insert two similar platinum wire or foil electrodes into the cell and connect to the apparatus of Fig. 16.17. Apply 0.10 volt across the electrodes. Adjust the range of the micro-ammeter to obtain full-scale deflection for a current of 10-25 milliamperes. Stir the solution with a magnetic stirrer. Add the iodine solution from a 5 mL semimicro burette slowly in the usual manner and read the current (galvanometer deflection) after each addition of the titrant. When the current begins to increase, stop the addition then add the titrant by small increments of 0.05 or 0.10 mL. Plot the titration graph, evaluate the end point, and calculate the concentration of the thiosulphate solution. It will be found that the current is fairly constant until the end point is approached and increases rapidly beyond. 

Carboxylic acids can be converted by anodic oxidation into radicals and/or carbo-cations. The procedure is simple, an undivided beaker-type cell to perform the reaction, current control, and usually methanol as solvent is sufficient. A scale up is fairly easy and the yields are generally good. The pathway towards either radicals or carbocations can be efficiently controlled by the reaction conditions (electrode material, solvent, additives) and the structure of the carboxylic acids. A broad variety of starting compounds is easily and inexpensively available from natural and petrochemical sources, or by highly developed procedures for the synthesis of carboxylic acids. 

Figure I.t. Cells used for laboratory scale electrochemical preparations (a) a beaker-type cell (b) an H-type cell.

Analysis of solutions. Pipette 20 ml of sample and standard solutions into 50-ml beakers, then pipette 1 ml releasing agent solution into each beaker and mix. If readings are off-scale, pipette 5 ml extract plus 15 ml M ammonium ethanoate and the 1 ml releasing agent and retest. Whatever dilution is necessary, ensure the sample plus M ammonium ethanoate solution add up to 20 ml before addition of the 1 ml releasing agent. 

For laboratory scale conversions a simple beaker-type cell (Fig. 1) is convenient When lower current densities have to be applied or in big scale operations 21,26) the Swiss-roll cell is of advantage. The latter cell (Fig. 2) contains a rolled-up sandwich, consisting of an anode and cathode sheet and a separator net. This allows a high electrode area applied in a small cell volume, which results in the low current densities necessary for efficient electrolyses at the nickel hydroxide electrode. 

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