Composites stoichiometry

Some laboratories do not have access to mass spectrometric analysis, but the number is fewer as the cost for this type of instrumentation is decreasing. It is suggested that these laboratories utilize amino acid analysis due to reduced cost and rapid turnaround. Peptide composition and stoichiometry can be determined, the technique is highly reproducible, and can be used to monitor cycle-to-cycle coupling efficiency. However, not all amino acids are recovered quantitatively. Cys and Trp are totally destroyed and must be quantitated using distinctly different hydrolysis procedures. Ser and Thr can be partially destroyed. Some laboratories perform amino acid analysis in addition to mass spectrometric analysis in order to assure peptide composition, stoichiometry, and quantity (see also Sections 7.3, 7.3.1 and 7.3.2). 

Composition, stoichiometry, electrical conductivity, apparent energy of activation of conductivity, surface area, and color of the oxide are presented in Table I together with the values for the oxide prepared at 200°C., according to the same procedure. 

The word stoichiometry is derived from the Greek stoicheion, which means first principle or element, and metron, which means measure. Stoichiometry describes the quantitative relationships among elements in compounds (composition stoichiometry) and among substances as they undergo chemical changes (reaction stoichiometry). In this chapter we are concerned with chemical formulas and composition stoichiometry. In Chapter 3 we shall discuss chemical equations and reaction stoichiometry. 

Composition stoichiometry Describes the quantitative (mass) relationships among elements in compounds. 

Stoichiometry Description of the quantitative relationships among elements in compounds (composition stoichiometry) and among substances as they undergo chemical changes (reaction stoichiometry). 

In Chapter 2 we studied composition stoichiometry, the quantitative relationships among elements in compounds. In this chapter as we study reaction stoichiometry— the quantitative relationships among substances as they participate in chemical reactions—we ask several important questions. How can we describe the reaction of one substance with another How much of one substance reacts with a given amount of another substance Which reactant determines the amounts of products formed in a chemical reaction How can we describe reactions in aqueous solutions ... 

The Dalton theory of the atom and related ideas were the basis for our study of composition stoichiometry (Chapter 2) and reaction stoichiometry (Chapter 3), but that level of atomic theory leaves many questions unanswered. Why do atoms combine to form compounds Why do they combine only in simple numerical ratios Why are particular numerical ratios of atoms observed in compounds WToy do different elements have different properties WToy are they gases, liquids, solids, metals, nonmetals, and so on Why do some groups of elements have similar properties and form compounds with similar formulas The answers to these and many other fascinating questions in chemistry are supplied by our modern understanding of the nature of atoms. But how can we study something as small as an atom ... 

Alloy compositions, stoichiometry Little or no control Alloy composition can be more tightly controlled... 

---