Stoichiometry mole ratio

When the new compound substitutes, even partially, for the original compound, the pseudomorph is called a substitutional pseudomorph. Usually the new compound has an ion in conunon with the original, as is the case of goethite pseudomorph after pyrite (both contain iron as Fe in goethite and as Fe in pyrite) and the malachite pseudomorph after azuiite (both contain Cu, COs ", and OH ) shown in Figure 110. The malachite pseudomorph is particularly interesting, because the two minerals differ only in the stoichiometry (mole ratio) of the ions present. 

Mole-ratio plots used to determine the stoichiometry of a metal-ligand complexation reaction. 

A procedure for determining the stoichiometry between two reactants by preparing solutions containing different mole ratios of two reactants. 

Both the method of continuous variations and the mole-ratio method rely on an extrapolation of absorbance data collected under conditions in which a linear relationship exists between absorbance and the relative amounts of metal and ligand. When a metal-ligand complex is very weak, a plot of absorbance versus Ay or n-J m may be curved, making it impossible to determine the stoichiometry by extrapolation. In this case the slope ratio may be used. 

This experiment describes the use of FIA for determining the stoichiometry of the Fe +-o-phenanthroline complex using the method of continuous variations and the mole-ratio method. Directions are also provided for determining the stoichiometry of the oxidation of ascorbic acid by dichromate and for determining the rate constant for the reaction at different pH levels and different concentration ratios of the reactants. 

The stoichiometry product does not agree with that used in the experiment, as Ni and B compounds are mixed in diethylether in a 1 1 mole ratio. The (Ph3P)2NiBPh2 0.5 OEt2 product is a dimer with a Ni — B—Ni multicentered bond. ... 

The rules of stoichiometry also apply in this case. In electrochemical cells, we must consider not only the stoichiometry related to chemical formulas, but also the stoichiometry related to electric currents. The half-reaction under consideration not only involves 1 mol of each of the copper species, but also 2 mol of electrons. We can construct a mole ratio that includes moles of electrons or we could construct a mole ratio using faradays. A faradav (F) is a mole of electrons. Thus, we could use either of the following ratios for the copper half-reaction ... 

A stoichiometry calculation is thus essentially a three-step procedure in which 1) the weight of D is divided by its formula weight to get moles of D, 2) the moles of D are converted to the moles of A by multiplying by the mole ratio a/d, as found in the chemical equation, and 3) the moles of A are converted to grams of A by multiplying by the formula weight of A. 

The same mole ratio, a/d, can also be found by simply balancing the common element in the formulas of A and D. Thus, the ratio, a/d, is the same as the ratio QS/QK seen in the equation for a gravimetric factor derived in Section 3.6.3 (Equation (3.12)) and is used to convert the weight of one substance to the weight of another, just as we described in Chapter 3 was the purpose of the gravimetric factor. Thus the concept of a gravimetric factor is based on stoichiometry. 

So, by measuring the current and the time for which it flows, we can determine the moles of electrons supplied. By combining the number of moles of electrons supplied with the mole ratio from the stoichiometry of the electrode reaction, we can deduce the amount of product obtained (see 1). 

We need to calculate the amount of methyl tert-bu tyl ether that could theoretically be produced from 26.3 g of isobutylene and compare that theoretical amount to the actual amount (32.8 g). As always, stoichiometry problems begin by calculating the molar masses of reactants and products. Coefficients of the balanced equation then tell mole ratios, and molar masses act as conversion factors between moles and masses. 

Complex stoichiometry problems should be worked slowly and carefully, one step at a time. When solving a problem that deals with limiting reactants, the idea is to find how many moles of all reactants are actually present and then compare the mole ratios of those actual amounts to the mole ratios required by the balanced equation. That comparison will identify the reactant there is too much of (the excess reactant) and the reactant there is too little of (the limiting reactant). 

The mole is the chemist s counting unit. Working with the mole should be second nature to students, so let s review grams to mole calculations since they are very important in mass-mass stoichiometry and the balanced equations provides mole ratios not mass ratios. 

Polymer complex Reagent mole ratio monomer halogen Polymer composition (elemental analysis) Conductivity cr(S cm1) Deconvoluted halogen spectra" XPS surface stoichiometry N halogen ratio Nls spectra components (B.E. > 401 eV)... 

Occasionally, not all equilibrium concentrations are known. When this occurs you must use equilibrium concepts and stoichiometry concepts to determine K. What you are trying to do in these problems is determine the amounts of materials at equilibrium. In Chapter 12, you learned that the balanced chemical equation shows you the relative amounts of reactants and products during the chemical reaction. For a reaction at equilibrium, the logic is the same. The mole ratios still apply. There is one major difference, however, between the stoichiometry... 

Mole ratio (stoichiometry) the ratio of moles of one substance to moles of another substance in a balanced chemical equation. (3.8)... 

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