Open beaker

Alternatively, if it is not desired to collect the iodobenzene, the iodosobenzene can be added to about 150 ml. of water contained in an open beaker or conical flask, and the mixture gently boiled until a clear solution is obtained and the pale yellow colour has disappeared. On cooling the iodoxybenzene rapidly separates. 

The filtrates from the decomposition of the brucine salts with dilute hydrochloride acid should be carefully preserved. The brucine Is recovered by the addition of an excess of dilute ammonia solution (1 4) if the solution becomes turbid before all the ammonia solution is added, introduce a little alcohol until the solution becomes clear. After several hours in an open beaker, filter oft the brucine, wash it well with cold water and dry it in the air. 

Fluorescein [9-(o-carboxyphenyI-6-hydroxy-3//-xantbene-3-one] [2321-07-5] M 320.0, 4950111 7.84 X 10 (in lO M NaOH), pK, 2.2, pKi 4.4, pKj 6.7. Dissolved in dilute aqueous NaOH, filtered and ppted by adding dilute (1 1) HCl. The process was repeated twice more and the fluorescein was dried at 100°. Alternatively, it has been crystd from acetone by allowing the soln to evaporate at 37° in an open beaker. Also recrystd from EtOH and dried in a vacuum oven. 

Zinc powder (32.8 g,0.5 moles) is washed successively with hydrochloric acid (3%, 4 X 25 ml), distilled water (4 x 30 ml), aqueous copper sulfate (2%, 2 X 50 ml), distilled water (4 x 30 ml), absolute ethanol (4 x 30 ml) and absolute ether (5 x 25 ml). The washings are performed conveniently by stirring a mixture of the zinc powder and each wash solution with a porcelain spatula in an open beaker and then decanting the supernatant liquid. The couple is finally transferred to a Buchner funnel, washed with additional anhydrous ether, and then vacuum-dried in a round-bottom flask. 

In the combustion reaction as carried out in the calorimeter of Figure 7-2, the volume of the system is kept constant and pressure may change because the reaction chamber is sealed. In the laboratory experiments you have conducted, you kept the pressure constant by leaving the system open to the surroundings. In such an experiment, the volume may change. There is a small difference between these two types of measurements. The difference arises from the energy used when a system expands against the pressure of the atmosphere. In a constant volume calorimeter, there is no such expansion hence, this contribution to the reaction heat is not present. Experiments show that this difference is usually small. However, the symbol AH represents the heat effect that accompanies a chemical reaction carried out at constant pressure—the condition we usually have when the reaction occurs in an open beaker. 

Dynamic Wilhelmy wettability tests on single component systems, such as hexadecane/water/glass, can be done quickly in open beakers. 

Figure 7. Wetting cycles of crude oil SS1473 tested in an open beaker. (Reproduced with permission from ref. 21. Copyright 1988 Society of Petroleum Engineers.)...

The reactions were performed in an open beaker using a domestic MW oven, and reaction times were reduced from 2-24 h of conventional reflux to 3-11 min under MW irradiation. 

Stadler and Kappe [52] re-examined this synthesis using a Milestone ETHOS 1600 series MW reactor [23] with on-line temperature and pressure control in order to investigate the existence of a nonthermal MW effect. They found, however, that when the reactions were performed under the action of MW heating using a reflux condenser no significant rate increase occurred over conventional reflux at the same temperature (80 °C). They confirmed that there was an increase in rate and yield when the reaction was performed in an open beaker, but this could readily be explained by evaporation of the solvent, causing an increase in temperature and concentration solution. It is to be noted that the same explanation applies for the appar-... 

MW irradiation conditions [80]. More recently, however, Varma and Kocevar s group have shown that a solvent-free and catalyst-free reaction of hydrazines with carbonyl compounds is possible upon MW irradiation (Scheme 6.24) [81]. Interestingly, the general reaction proceeds smoothly even for solid reactants and is completed below the melting points of the two reactants possibly via the formation of a eutectic. The reactions have been conducted in household MW oven and the control experiments are conducted concurrently in separate open beakers the reactions can be essentially followed by visual observation when a melt is obtained [82],... 

This increase in the entropy S of a gas explains why an open beaker of thionyl chloride SOCI2 in the laboratory appears to be smoking. ... 

The Mel-Temp apparatus (Fig. 33) substitutes for the Thiele tube or open beaker and hot oil methods (see Using the Thiele Tube ). Before you use the apparatus, there are a few things you should look for. 

Get some of your eluent and prewet the adsorbant somewhat. For about 10 g of adsorbant, start with 3 - 5 g of the liquid eluent. (Oh. Did anyone ever tell you, you can weigh liquids directly, just like solids ) Now add the eluent to the adsorbant and mix like mad. You can see the advantage of a screw-cap bottle over an open beaker. The powder can t fly out of a closed bottle. Do not add too much eluent You only want to precondition the adsorbant so that you don t get bubbling in the column from the heat of hydration released when you eventually run the experiment. 

Stirring NaOCl/NaOH solutions in open beakers in the absence of magnetic beads did not result in any decrease in the hypochlorite concentration. When ungrafted magnetic beads were added there was still no significant decrease over several hours. Thus the 1.5 1 ratio is not an artefact due to loss of CI2 or reaction of hypochlorite with the PVA core. 

The system remains at equilibrium as long as the container is not opened. Note that small changes to the components of a system are sometimes negligible. Thus, equilibrium principles can be applied if a system is not physically closed. For example, consider the equilibrium of a solid in a saturated aqueous solution, such as CaO(s) + H20( ) Ca (aq) + 20H (aq). You can neglect the small amount of water that vaporizes from the open beaker during an experiment. 

Figure 7. Polythene Beaker Used in Germination Experiments A, Plastic cover B, Seeds C, Filter Paper D, Open beaker employed in the "volatiles method" (13) (by permission of Blackwell Scientific Publications).

There is a sequence of experimental techniques ranging from the open beaker on the bench to the extremely rigorous h.v.t. used for studying the kinetics of radiation-induced cationic polymerisations. Each technique in the series has its characteristic level of extraneous materials, and as the level of cleanliness is raised, there is a concurrent loss of flexibility. 

The chloroaluminate ionic liquids are water sensitive. When you expose them to air, they produce HCl. The tetrafluoroborates and hexafluorophosphates, on the other hand, are air and water stable. They can be worked with in an open beaker. Because they are nonvolatile, there is no smell, and they can be used in high-vacuum systems. 

E.H. Barry of NY told to Mr Cohn of Franklin Institute that, in order to.test the stability of silvering sola it was allowed. to stand over the weekend in dosed room, in an open beaker. On Monday morning the contents and the beaker fragments were found to have been scattered all over the ceiling. A similar accident was described... 

It is significant that a hydriding power equivalent to 20-30 atm. of H2 is obtained in a reaction of this kind using aqueous BH4 in an open beaker. 

What will happen to the sodium sulphide if it is left in an open beaker Explain the processes occurring in a sodium hydroxide solution when hydrogen sulphide is passed through it. 

In an open beaker containing a magnetic stir bar, 1.8 g (0.010 mole) of ethylenediamine-iV.N -diacetic add is neutralized with 0.80 g of sodium hydroxide in 10 mL of water and diluted with 25 mL of ethanol. o-Acetoxy-benzyl bromide4 (4.6 g, 0.020 mole) is added. The clear solution is maintained... 

An open beaker of pure water, under ordinary atmospheric pressure, contains a glass tube to which is attached a semipermeable membrane filled with an aqueous solution of, for example, sugar (or salt or other solute of low volatility). As its name implies, the membrane... 

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