Solution bumped

Add 4 to 5 porcelain boiling chips to the flask. (NOTE Do not add boiling chips to a hot solution later on). Boiling chips produce a stream of air bubbles when they are heated, which reduces the possibility of the solution "bumping". 

A student was removing and disassembling a reflux condenser when the solution bumped and splashed the solution onto her face and chest. She was wearing chemical splash goggles but a poor seal of the goggles with her face still allowed some solution to enter her eyes. She was ushered to a safety shower and eventually examined at an emergency room. There was no permanent damage to her eyes. 

When she removed the reflux condenser, the solution bumped... splashing her face and chest. In spite of the fact that the student was wearing goggles, the solution managed to go past the seal and into her eyes."... 

Place 2 1 ml. (measured from a micro-burette) of nitro-benzene and 5 g. of granulated tin in a 150 ml. round-bottomed flask fitted with a small reflux water-condenser. (A large flask is employed because the mixture when subsequently boiled may bump violently.) Pour 10 ml. of cone. HCl down the condenser on this scale the reaction is not sufficiently vigorous to get out of control. Heat over a gauze for 15 minutes. Cool the flask and add a solution of 7 5 8- of NaOH in 10 ml. of water to redissolve the initial precipitate. Add about... 

Place about o-i g. of the following substances in a boiling tube and add about 5 ml. of 10% aqueous NaOH solution. Note any reaction in the cold. Then add a small piece of unglazed porcelain (to prevent bumping ), and boil gently for a few minutes. Note any further reaction. 

Climb unlocks dislocations from the precipitates which pin them and further slip (or glide ) can then take place (Fig. 19.3). Similar behaviour takes place for pinning by solute, and by other dislocations. After a little glide, of course, the unlocked dislocations bump into the next obstacles, and the whole cycle repeats itself. This explains the progressive, continuous, nature of creep, and the role of diffusion, with diffusion coefficient... 

Diethyl-p-nitrobenzyl-phthalimidomalonate (70 g) and sodium carbonate (70 g) in water (700 ml) were refluxed overnight with mechanical stirring (to avoid bumping). The clear brown solution was acidified with hydrochloric acid and refluxing and stirring were continued for a further 40 minutes. The mixture was cooled and the colorless precipitate (31 g) collected. A second crop (18.5 g) was obtained on evaporation of the mother liquors. Crystallization from aqueous ethanol gave the compound N-carboxybenzoyl-p-nitro-DL-phenylalanine as small needles, MP 198° to 200°C. 

Buffer action 46 Buffer capacity 48 Buffer mixture universal, (T) 831 Buffer solutions 46, (T) 831 acetic acid-sodium acetate, 49 for EDTA titrations, 329 preparation of IUPAC standards, 569 Bumping of solutions 101 Buoyancy of air in weighing 77 Burette 84, 257 piston, 87 reader, 85 weight, 86... 

The results obtained demonstrate competition between the entropy favouring binding at bumps and the potential most likely to favour binding at dips of the surface. For a range of pairwise-additive, power-law interactions, it was found that the effect of the potential dominates, but in the (non-additive) limit of a surface of much higher dielectric constant than in solution the entropy effects win. Thus, the preferential binding of the polymer to the protuberances of a metallic surface was predicted [22]. Besides, this theory indirectly assumes the occupation of bumps by the weakly attracted neutral macromolecules capable of covalent interaction with surface functions. 

The inlet tube, preferably in the center neck, is placed in such a way that it nearly touches the bottom of the flask. Thereby nitrogen bubbles effect some agitation of the reaction mixture and prevent bumping of the boiling solution. 

The tryptophane is extracted from the aqueous solution by repeatedly shaking in a separatory funnel with 25-cc. quantities of ra-butyl alcohol water is added from time to time to keep the volume approximately constant (Note n). The butyl alcohol extract is distilled under reduced pressure. After the water present has distilled over, the tryptophane precipitates in the distilling flask and may cause bumping. When all water has been removed, as is indicated by non-formation of drops on the side of the condenser, the distillation is stopped, and, after cooling, the tryptophane is filtered off and washed with a little fresh butyl alcohol. Such extractions ami distillations are con-... 

Glass wool is placed in the solution, in the neck of the alembic distillation column, and at the top of the column to inhibit bumping during the distillation. 

Figure 12. The structures of two trans diols of benz[a]anthracene showing the diequatorial conformation of the unhindered 10,11-diol and the diaxial conformation of the hindered 1,2-diol. These trends persist in solution where the 10,11-diol exists as an equilibrium of 30% axial and 70% equatorial conformers (that is, the ring is flexible) on the other hand the 1,2-diol is 100% diaxial even in solution. If the 1-hydroxyl group were equatorial it would "bump" into the hydrogen atom on Cl2.

---