Mixture homogeneity

The conditions under which the material is tested are crucial. The top of the exposure chamber must be sealed and the tank should contain no free air space. A stirring mechanism in the tank keeps the leachate mixture homogeneous and a heater block keeps it at an elevated temperature as required for the test. Stress conditions of the material in the field should also be simulated as closely as possible. The original U.S. EPA Method 9090 test included a rack to hold specimens under stress conditions but was revised when some materials shrank in the leachate. Due to the hazardous nature of the material, testing should be performed in a contained environment and safety procedures should be rigorously followed. 

EXAMPLE 1.2. A teaspoon of salt is added to a cup of warm water. White crystals arc seen at the bottom of the cup. Is the mixture homogeneous or heterogeneous Then the mixture is stirred until the salt crystals disappear. Is the mixture now homogeneous or heterogeneous ... 

Blanco ° proposed the use of the mean square difference between two consecutive spectra plotted against the blending time in order to identify the time that mixture homogeneity was reached. 

We used an oil bath (200 mm ID x 200 mm height) for the Ullmann-coupling in order to heat the reaction mixture homogeneously. The reaction vessel was deeply immersed in the oil bath. The bath temperature was strictly controlled by Thermo Minder DH-12 (TAITEC Co., Ltd, Saitama, Japan). 

There are currently no mathematical techniques to predict blending behavior of granular components without prior experimental work. Therefore, blending studies start with a small scale, try-it-and-see approach. The first portion of this chapter is concerned with the following typical problem a 5-ft - capacity tumble blender filled to 50% of capacity and run at 15 rpm for 15 minutes produces the desired mixture homogeneity. What conditions... 

Use the Mixtures and Compounds activity (eChapter 2.7) to develop a flow chart for identifying substances as heterogeneous mixtures, homogeneous mixtures, compounds, or elements. 

Heat a mixture of 65 g (0.5 mol) of dry octan-2-ol (b.p. 178-180°C), 74 g (0.5 mol) of pure phthalic anhydride (1) and 40 g of dry pyridine (CAUTION) on a water bath for 1 hour, and allow to cool. Dissolve the resulting viscous mass in an equal volume of acetone. Add slowly, preferably with stirring, 55 ml of concentrated hydrochloric acid diluted with an approximately equal volume of crushed ice if an oil separates before all the hydrochloric acid has been added, introduce more acetone to render the mixture homogeneous. Add ice-water until the oil is completely precipitated this usually sets to a hard mass within 1-2 hours. If the resulting mass is semi-solid or pasty (2),... 

In the wet process, the solid material, after dry crushing, is reduced to a fine state of division in wet tube or ball mills and passes as a slurry through bowl classifiers or screens. The slurry is pumped to correcting tanks, where rotating arms make the mixture homogeneous and allow the final adjustment in composition to be made. 

Quantitatively evaluate blend uniformity or homogeneity to determine optimum mixing time. Typically, a measure based on total mixture homogeneity is used as the means to track the evolution of mixture quality in blenders. There are three key factors to consider ... 

Johnson MCR. 1975. The effect of particle size upon mixture homogeneity. Pharm. Acta Helv. 50 60-63. 

The definitions of the degree of mixing presented above aim at a local characterization of the mixture homogeneity in the physical space. There also exist more indirect mixing indices. The segregation index J of Danckwerts (12) is one of the most famous ones. It applies to continuous reactors and relies upon the variance of age J = Var oip/Var a>where a is the age of a molecule,... 

Homogeneous Mixtures Homogeneous mixtures have the same composition and properties throughout the mixture and are also known as solutions. They have a uniform color and distribution of solute and solvent particles throughout the mixture. 

In the case of ware with less demanding requirements for mixture homogeneity (bricks, drain pipes, etc.), mixing is carried out with a pan mill which is suitable for the preparation of press mixtures as well as plastic bodies. As the treatment causes considerable entrapment of air in the mixture, it is usually linked up to a vacuum extruder where the mix has air removed, is kneaded and preformed or is given its final form. 

Unlike heterogeneous mixtures, homogeneous mixtures do have a uniform composition. By this I mean that the composition of an entire sample is consistent. If you were to take one scoop out of one area of a homogenous mixture and a second scoop out of a different area of the same sample, the composition of each scoop would be essentially the same. 

See mixture homogeneous chemical reaction. (2) Loosely, a product formula (often proprietary) of... 

In a typical experiment 80 mg of FS03H was introduced into a dry clean proton NMR tube at -115° followed by condensation of SOjCIF ( 0.35 ml). With the aid of a cooled glass rod 30 mg of precursor was introduced and the resultant mixture homogenized. Appropriately larger amounts were used for the 13C NMR than for the H NMR spectra. Immediately after the generation of the cations the samples were inserted into the precooled NMR probe. The temperatures at which the spectra were recorded were measured using... 

Real membrane systems to be used in practice usually do not have the simple architecture assumed in the preceding quantitative treatments (single-wall, non-supported) nor do they fulfil basic boundary conditions, i.e. well mixed gas mixtures, homogeneous gas compositions and pressure (no gradient) across the membrane length (flow direction of feed/permeate). In those cases the aerodynamic conditions of the feed and permeate flow, the precise design and the type of permeate removal (sweep gas, vacuum suction) are important. 

We start with studies that aim to overcome solubility problems when a typical metathesis reaction is transferred into water. The first way to introduce water is to use a solvent pair capable of rendering the reaction mixture homogeneous. For example, after an optimization study, the Hoveyda catalyst 68 was found to promote the RCM of various dienes in aqueous DME and acetone solutions. Under these homogeneous conditions, substrates with various substituents underwent RCM to form five-, six- and seven-membered cyclic products. 

Solid, liquid, gas, element, compound, mixture, homogeneous, heterogeneous... 

The following list includes several items. Which three of the following terms apply to each one Solid, liquid, gas, element, compound, mixture, homogeneous, heterogeneous... 

---