Addition of liquids

2 Addition of Liquids The controlled addition of a liquid reagent to a reaction mixture is most easily accomplished through the use of a 

Robots usually Include a special addition unit for dispensing liquids such as solvents, diluents and reagent solutions to the sample flask. Such a unit normally consists of one or several systems made up of a solution reservoir, a high-precision syringe and a T-shaped valve that can be switched between two 

---

By the addition of liquid bromine to a warm mixture of the alcohol and purified red phosphorus ... 

Fixed-roof atmospheric tanks require vents to prevent pressure changes which would othei wise result from temperature changes and withdrawal or addition of liquid. API Standard 2000, Venting Atmospheric and Low Pressure Storage Tanks, gives practical rules for vent design. The principles of this standard can be applied to fluids other than petroleum products. Excessive losses of volatile liquids, particularly those with flash points below 38°C (100°F), may result from the use of open vents on fixed-roof tanks. Sometimes vents are manifolded and led to a vent tank, or the vapor may be extracted by a recov-eiy system. 

If the addition of liquid to the tank causes an average endothermic or exothermic heat of solution, q J/kg (Btii/lb) of m eiip, it may be included by adding q,/co to both the numerator and the denominator of the left side. The snbscrmt 0 refers to the makeup. 

On the other hand the addition of liquids to the polymer will cause separation of the chains and increase their general mobility. This is the effect of... 

In the laboratory, a range of slush baths may be used for speciality work. These are prepared by cooling organic liquids to their melting points by the addition of liquid nitrogen. Common examples are given in Table 8.2. Unless strict handling precautions are instituted, it is advisable to replace the more toxic and flammable solvents by safer alternatives. 

Flexibilized epoxy resins are important structural adhesives [69]. Liquid functionally terminated nitrile rubbers are excellent flexibilizing agents for epoxy resins. This liquid nitrile rubber can be reacted into the epoxy matrix if it contains carboxylated terminated functionalities or by adding an amine terminated rubber. The main effects produced by addition of liquid nitrile rubber in epoxy formulations is the increase in T-peel strength and in low-temperature lap shear strength, without reducing the elevated temperature lap shear. 

Seraper blades set to rotate at 35 rpm are used for a pilot plant addition of liquid ingredients into a body-wash produet. What should the speed of the blades be in a full-seale plant, if the pilot and the full-seale plants are geometrieally similar in design Assume seale-up is based on eonstant tip speed, diameter of the pilot plant seraper blades is 0.6 m, and diameter of the full-seale plant seraper blades is 8 ft. 

The addition of liquids or solutions to the reaction vessel can usually be carried out by use of a simple dropping funnel surmounted, if necessary, by a drying tube. For reactions carried out under pressure, vacuum, or an inert atmosphere, a pressureequalizing dropping funnel is required (Fig. A3.3). Care must be exercised in either case since a single setting of the stopcock will result in a decreased rate of addition as the liquid head diminishes. 

Zuguss, m. infusion addition (of liquid), zugutemachefit v.i. work up, work (ores, etc.), zugutefletzt, adv. last, finally. 

Small amounts (usually <10%) of plasticizer could be used in the blending system to improve the processing properties of the material by lowering the melting and glass-transition temperatures. The addition of liquid plasticizer also makes the material soft but at the same time, the strength and toughness of the material decreases. 

Micrometer syringe pipettes are fitted with a micrometer head which operates the plunger of the syringe, and when fitted with a stainless steel needle tip can be used for the dropwise addition of liquid the volume added is recorded by the micrometer. 

Two cases may be considered to illustrate the use of enthalpy-humidity charts. These are the mixing of two streams of humid gas and the addition of liquid or vapour to a gas. 

Preparation ofKF-2HF. This is prepared by carefully adding hydrogen fluoride vapor mixed with nitrogen to solid potassium bifluoride.13 Potassium bifluoride is available in convenient quantities from some supply houses (Aldrich 23,928-3, for example). The addition of hydrogen fluoride vapor to potassium fluoride is extremely exothermic and is best not attempted. The addition of liquid hydrogen fluoride to potassium bifluoride is also extremely exothermic and is best not attempted. 

In any consideration of stereoselectivity in radical addition to acylic substrates, interpretation of the results is complicated by the knowledge that alkenes may be converted, at least in part, into their geometrical isomerides by traces of bromine (or of HBr, i.e. by Br, cf. p. 315). This may, however, be minimised by working at low temperatures, and by using a high concentration of HBr. Thus addition of liquid HBr at -80° to cis 2-bromobut-2-ene (67) was found to proceed with high TRANS stereoselectivity, and to yield (68) almost exclusively ... 

Bromochloromethane was being prepared in a 400 1 reactor by addition of liquid bromine to dichloromethane in presence of aluminium powder (which would form some aluminium bromide to catalyse the halogen exchange reaction). The reaction was started and run for 1.5 h, stopped for 8 h, then restarted with addition of bromine at double the usual rate for 2.5 h, though the reaction did not appear to be proceeding. Soon afterwards a thermal runaway occurred, shattering the glass components of the reactor. 

Accidental addition of liquid oxygen to vacuum jars containing acetone residues from trap-cooling use caused a violent explosion. Liquid nitrogen is less hazardous as a trap coolant, but only under controlled conditions. 

Addition of liquid air to ether in a dish caused a violent explosion after a short delay. Previous demonstrations had been uneventful, though it was known that such mixtures were impact- and friction-sensitive. 

Near the endpoint, when you see the indicator change colour as liquid enters the flask from the burette, slow the addition of liquid. The endpoint can occur very quickly. 

The action of water in the titanium tetrachloride catalyzed polymerization is paradoxical, since water at —60 to —80° was present only in the solid phase its solubility in hexane at these temperatures is in the order of 10-10 moles per liter (Plesch et al., 83). It was found to be essential that the water be present as an extremely fine dispersion such as might result from the rapid bubbling of moist air through the liquid at the low temperature. Addition of liquid water which formed lumps of ice in the reaction mixture did not initiate polymerization. It may be concluded that a fine dispersion is necessary in order that reaction with titanium tetrachloride can occur and a chain reaction is initiated ... 

For addition of liquid bromine, a 5-mL piston burette was used delivering 0.4629 p.L s . In the calorimeter was placed 400 mL of a 0.4 M alkylmagnesium bromide in diethyl ether. The measuring procedure followed the same principles as used for HBr addition. 

Sometimes particles are encouraged to agglomerate to yield granules, for example, for pharmaceutical applications which may require the addition of liquids or other binders. In the ceramics, paint, plastics and rubber industries, however, reducing or eliminating agglomerate formation is of overriding importance. 

However, Weaire et al. [41] have recently shown that it is possible to produce monodisperse dry foams containing Kelvin polyhedra. Upon addition of liquid, a structural rearrangement occurs at 0.87, to a system made up of mainly pentagonal faces. Thus, it would seem that a transition from pentagonal dodecahedral to tetrakaidecahedral packing may take place on reduction of foam liquid content. 

Nitromethane (Vol. I, p. 579) may be used as a monergol propellant. However its negative oxygen balance may be reduced by the addition of liquid oxidants, e.g. of tetranitromethane to form a bipropellant. In practice, however, nitromethane decomposes too slowly, and it is difficult therefore to obtain hypergolic mixtures from it. To facilitate and accelerate the decomposition of mixtures with nitromethane it is necessary to add a catalyst, such as a salt of chromic acid. 

The reaction between MC35 and liquid N2Os resulted in the moisture sensitive tris(nitrato)oxo compounds [M0(N03)3].1 The (NMe4)[Nb0(N03)4] complexes were prepared by addition of liquid N2Os to the appropriate hexachloro complexes with covalently bonded... 

---