Bottom of a Container

Some students thought that atoms sink to the bottom of a container (choice A) when something changes from the solid to the liquid state, or some float on the surface (choice B). 

Fig. 1.6 The radius of curvature on the bottom of a container is smallest on the beaker, greater on the Erlenmeyer, and largest on the round-bottom flask.

Steam is one of the safest and easiest techniques to provide even, uniform heat in the lab. Because steam can provide an even heat distributed uniformly across the entire bottom of a container, there are no fears of hot spots or solution superheating. In addition, the steam bathf is made up of simple components with no electrical wires or moving parts. Thus, there is nothing to wear out or to be damaged in a steam bath by accidental spills of heated materials. 

Once a correct sample has been defined, it must be correctly taken. An extraction error occurs if the sample that has been identified cannot be obtained. In other words, a delimitation error may be avoided by defining a correct boundary for the sample, but if it cannot actually be recovered, then an extraction error is incurred. One of the main impediments to extracting the defined sample is the equipment used. It is especially difficult to sample material in three dimensions such as that in a tank, rail car, landfill, or 100 g of powder in the lab. To obtain a random sample, the bottom of a container as weU as the top must be accessible. While sampling from the top is generally easy and from the bottom difficult, getting a theoretically predefined sample of material from the middle is virtually impossible For liquids, dropping a bottle to the desired depth of a large tank or drum is one way to approximate this, but for solids no practical technique that is also theoretically sound has been developed. 

Free-falling film technique. The liquid under investigation is allowed to flow through a narrow slit in the bottom of a container under such conditions that it forms a free-falling film. Nylon wires at both sides of the film stabilize it during its downward movement. The film becomes thinner during its fall due to its increased velocity. The expansion of the film is related to the vertical velocity gradient... 

Cut Whatman No. 540 paper to fit bottom of a container which is placed in a water bath of 60 °C. 

All of the molecules in a solution are subjected to agitation forces, known as Brownian motion, that tend to make them occupy the maximum amount of available space. A solid that dissolves in a liquid is dispersed throughout the entire volume and is thus uniformly distributed. The Brownian motion of colloidal particles is slower. If they are put into the bottom of a container, they diffuse very slowly through the mass of the liquid. 

For example, the densities of mercury (13.5 g/ml) and water (1.0 g/ml) are very different relative to each other. This relative density difference (sometimes called specific gravity) causes mercury to sink to the bottom of a container filled with water. 

The topics included demonstrate how the behaviour of powders is often quite different from the behaviour of liquids and gases. Behaviour of particulate solids may be surprising and often counter-intuitive when intuition is based on our experience with fluids. The following are examples of this kind of behaviour When a steel ball is placed at the bottom of a container of sand and the container is vibrated in a vertical plane, the steel ball will rise to the surface. 

For many years the Society of the Plastics Industry, Inc. (SPI) in the United States has romoted a voluntary coding system for the identification of the resins used in rigid plastic containers. The system comprising a number 1 to 7 and several letters is generally moulded into the bottom of a container. For example, the number 1 and the letters PETE indicates that the container is made of polyethylene terephthalate while the number 2 and the letters HDPE signify that the container is comprised of high density polyethylene. Thirty-nine U.S. states have mandated that plastic bottles 16 ounces or more and other rigid plastic containers of 8 ounces or more must carry the SPI resin code. 

Gases expand to fill their containers liquids do not. The strong attractions between liquid particles hold them together at the bottom of a container. 

Properties of gases. Suggest explanations for the fsicts that gases (a) are transparent, (b) do not setde to the bottom of a container, (c) diffuse through all the space available to them. 

Decantation, in which the solid portions of a mixture are allowed to settle to the bottom of a container, and the liquid portion is poured into another container... 

SLS and cause the surfactant to become significantly less water soluble. Surfactant solutions will typically become hazy and over time the surfactant can precipitate. If a surfactant precipitates, it is not available for foam generation, cleaning, wetting, etc. These surfactant properties require a surfactant be available at an interface, not sitting on the bottom of a container. SMEs are not affected by hard water. In other words, their divalent salts are water soluble. Sulfonated fatty acids are affected by hard water and can precipitate in cold water [3]. The effects of water hardness on detergency will be discussed later. 

The drop penetration test was developed by Sookne et al. [168]. The apparatus consists of a drop-forming device with capillaries mounted at the bottom of a container, a tube to shield the spray from draft, and a sample holder designed to collect the water penetrating the fabric. The time needed to collect 10 mL of water is measured. 

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