Mass or density

When the analytical method s selectivity is insufficient, it may be necessary to separate the analyte from potential interferents. Such separations can take advantage of physical properties, such as size, mass or density, or chemical properties. Important examples of chemical separations include masking, distillation, and extractions. 

That the cross-section of a jet of liquid from a non-circular orifice vibrates between the form of the orifice and a circle was first observed by Bidone.i This produces a series of waves. The explanation of the phenomenon as due to surface tension was given by BufF, the mathematical theory and experimental method being developed by Lord Rayleigh. Piccard and Meyer used the method for comparative measurements, refinements being introduced by Pedersen and Bohr. Rayleigh showed that for an ideal jet of radius r at its circular section, the time of oscillation is r=Ki(Qr layi where q is the density of the liquid. For an actual liquid r depends on the flow-rate and corrections are necessary. The period r is related to the directing force F and moment of inertia I by the equation t=7t(IIF) f. Since I is proportional to the mass or density and depends in an unknown way on the form of the orifice, and F is proportional to the surface tension a, it follows that r=7iA(Qla) where is a constant. Since r=l jn and where A=wave-... 

Centrifugation Can Separate Particles and Molecules That Differ in Mass or Density... 

A EXPERIMENTAL FIGURE 3-31 Centrifugation techniques separate particies that differ in mass or density, (a) In... 

Several times in the preceding sections we used the numerical results of measurements of the boiling points, masses, or densities of pure substances. These and hundreds of other kinds of measurements are fundamental to chemistry and every other science. The result of a measurement is what we refer to as quantitative information—it uses numbers. Weighing yourself is a quantitative experiment. By contrast, there is qualitative information that does not deal with numbers. For example, sticking your hand into a tub of water and determining it to be hot is a qualitative observation. 

Air ria.ssification The process of passing feed material through or past an air stream at a certain velocity to remove contaminants. The process generally works best with a process stream of dichotomous masses (or densities). 

Glycerin Doubling the pressure will not significantly influence the volume and will not influence the mass or density of a liquid. 

The ideal gas law can be appHed to determine the existing conditions of a gas sample when three of the four variables, P,V,T, and n, are known. It can also be used to calculate the molar mass or density of a gas sample. 

Knowledge of molecular size and flexibility explains how individual molecules behave when completely isolated. However, such isolated molecules are encountered only in theoretical studies of dilute solutions. In practice, molecules always occur in a mass, and the behavior of each individual molecule is very gready affected by its intermolecular relationships to adjacent molecules in the mass. Three basic molecular properties affect processing performances, such as flow conditions, that in turn affect product performances, such as strength or dimensional stability. They are (1) mass or density, (2) molecular weight (MW), and (3) molecular weight distribution (MWD). 

A hquid thermometer works on the principle that the specific mass or density is a function of the temperature. The volumetric expansion of the volume is therefore a measure for the increase in temperature. 

To find the desired probability that an event occurs use a probability density function when we have continuous random variables or a probability mass function in the case of discrete random variables. In this text, f(x) is used to represent the probability mass or density function for either discrete or continuous random variables, respectively. We now discuss how to find probabilities using these functions, first for the continuous case and then for discrete random variables. To find the probability that a continuous random variable falls in a particular interval of real numbers, we have to calculate the appropriate area under the curve of f(x). Thus, we have to evaluate the integral of f(x) over the interval of random variables corresponding to the event of interest. This is represented by ... 

Describe how to find the relationship between the state properties P, I/, T) of a gas and its molar mass or density. 

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