Homogeneous and Heterogeneous Mixtures

A similar situation occurs with ether and water (Experiment 13.2). 

If only a small amount of ether—colored brown with iodine—is added to water, a homogeneous brown-colored solution results as we have seen. This is because the 

Experiment 13.1 Demixing of phenol water. We let a hot mixture of phenol and water (at a ratio of 1 1) cool down in the air. After a while, demixing takes place thereby forming streaks. The phenol-rich phase settles to the bottom because of its higher density. The demixing becomes nicely visible when a tiny amount of methyl red is added to the original mixture. Because the dye is not soluble in water but is very soluble in phenol, it remains in the phase rich in phenol. 

Experiment 13.2 Mixing of ether with water. We add a small amount of ether— colored brown with a bit of iodine— to water in a separating funnel (at a ratio of 10 1), and subsequently, we shake the funnel gently. A homogeneous brown-colored solution results. When the same amount of ether is added once more (ratio now 5 1) and we shake the fuimel again, a large portion of the ether separates as a brown layer on top of the almost colorless water. 

Solid mixtures behave very similarly. For example, a-brass (an alloy of copper and up to 40 % zinc) can be preserved for just about any amount of time (Experiment 13.3). 

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There are some aspects of process design in which decisions are based primarily on past experience rather than on quantitative performance models. Problems of this type include the selection of constraction materials, the selection of appropriate models for evaluating the physical properties of homogeneous and heterogeneous mixtures of components, and the selection of safety systems. Advances in expert systems technology and information management will have a profound impact on expressing the solutions to these problems. 

In both homogeneous and heterogeneous mixtures involving cellulose, the system is likely to be rather complex, so that separation and identification of trapping products might prove difficult. 

Recognize various forms of matter homogeneous and heterogeneous mixtures, substances, compounds, and elements... 

Fig. 4.7. R.f.-driven ZAS experiment schematic diagram and application to a homogeneous and heterogeneous mixture of adamantane (a) and hexamethyethane (h) [76]. The appearance of cross-peaks, due to intermolecular spin diffusion between the two components, is seen clearly in the homogeneously mixed sample, while it is absent in the heterogeneous mixture, (Figure adapted from Ref. [33]).

Iced Tea Use iced tea with and without ice cubes as examples to explain homogeneous and heterogeneous mixtures. If you allow all of the ice cubes to melt, what type of mixture remains ... 

What is the difference between a homogeneous and heterogeneous mixture ... 

Processes of this type can be discussed in the same way as chemical reactions. The constituents of the mixture assume the role of elements as basic substances whose amounts are conserved during transformation (see Sect. 1.2). The homogeneous and heterogeneous mixtures themselves, however, correspond to chemical compounds. Therefore, the composition of these mixtures can be given by a content formula but with the peculiarity that the content numbers are not necessarily integer... 

During the chemical conversion of raw materials, homogeneous and heterogeneous mixtures (Figs. 1-2 and 1-3) are generated. Both reactants and products may be found in these mixtures, according to the yield and conversion of the chemical reaction. By means of thermal separation processes these mixtures must be treated to obtain the desired products to a demanded purity and to enable the raw materials to be recycled. 

Go to http //now.brookscole.com/ cracoliceSe and click Coached Problems for an exercise on Homogeneous and Heterogeneous Mixtures. 

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