Conservation, principle

As shown in the following examples, the application of conservation principles simplifies stoichiometric calculations. 

Using appropriate conservation principles, derive an equation relating the moles of C10H20N2S4 to the moles of NaOH. What is the weight percent C10H20N2S4 in a sample of Antabuse if the H2SO4 produced from a 0.4613-g portion reacts with 34.85 mb of 0.02500 M NaOH ... 

Stoichiometric relationships and calculations are important in many quantitative analyses. The stoichiometry between the reactants and products of a chemical reaction is given by the coefficients of a balanced chemical reaction. When it is inconvenient to balance reactions, conservation principles can be used to establish the stoichiometric relationships. 

Using conservation principles, write stoichiometric relationships for the following... 

In an indirect analysis the precipitate does not contain the analyte, but is the product of a reaction involving the analyte. Despite the additional complexity, a stoichiometric relationship between the analyte and the precipitate can be written by applying the conservation principles discussed in Section 2C. 

Quantitative Calculations In acid-base titrimetry the quantitative relationship between the analyte and the titrant is determined by the stoichiometry of the relevant reactions. As outlined in Section 2C, stoichiometric calculations may be simplified by focusing on appropriate conservation principles. In an acid-base reaction the number of protons transferred between the acid and base is conserved thus... 

Macroscopic and Microscopic Balances Three postulates, regarded as laws of physics, are fundamental in fluid mechanics. These are conservation of mass, conservation of momentum, and con-servation of energy. In addition, two other postulates, conservation of moment of momentum (angular momentum) and the entropy inequality (second law of thermodynamics) have occasional use. The conservation principles may be applied either to material systems or to control volumes in space. Most often, control volumes are used. The control volumes may be either of finite or differential size, resulting in either algebraic or differential consei vation equations, respectively. These are often called macroscopic and microscopic balance equations. 

Microscopic Balance Equations Partial differential balance equations express the conservation principles at a point in space. Equations for mass, momentum, totaf energy, and mechanical energy may be found in Whitaker (ibid.). Bird, Stewart, and Lightfoot (Transport Phenomena, Wiley, New York, 1960), and Slattery (Momentum, Heat and Mass Transfer in Continua, 2d ed., Krieger, Huntington, N.Y., 1981), for example. These references also present the equations in other useful coordinate systems besides the cartesian system. The coordinate systems are fixed in inertial reference frames. The two most used equations, for mass and momentum, are presented here. 

Inform the public about environmental conservation principles and encourage tlicir participation in environmental affairs... 

The conservation principle for mass and energy in the absence of external fields and internal sources or sinks is expressed as... 

The dependence on electron locahzation energy can also be illustrated by the use of the bond order conservation principle. This principle gives an approximate recipe to estimate changes in bond strength when coordination of a surface atom or adsorbate attachment changes [5, 15]. 

Compartmental soil modeling is a new concept and can apply to both modules. For the solute fate module, for example, it consists of the application of the law of pollutant mass conservation to a representative user specified soil element. The mass conservation principle is applied over a specific time step, either to the entire soil matrix or to the subelements of the matrix such as the soil-solids, the soil-moisture and the soil-air. These phases can be assumed in equilibrium at all times thus once the concentration in one phase is known, the concentration in the other phases can be calculated. Single or multiple soil compartments can be considered whereas phases and subcompartments can be interrelated (Figure 2) with transport, transformation and interactive equations. 

Feller, R. L., "The Deterioration of Organic Substances and the Analysis of Paints and Varnishes", in "Preservation and Conservation, Principles and Practices", Smithsonian Press, Washington, D.C., 1976, pp. 287-299. 

---