Balancing chemical equations using oxidation numbers

Balancing chemical equations using oxidation numbers... 

Write a balanced chemical equation for the reaction. Use oxidation numbers to identify the oxidizing agent and the reducing agent. 

In fact, you can use oxidation numbers to balance a chemical equation by a new method. The oxidation number method is a method of balancing redox equations by ensuring that the total increase in the oxidation numbers of the oxidized element(s) equals the total decrease in the oxidation numbers of the reduced element(s). 

Mole ratios You have seen that the coefficients in a chemical equation indicate the relationships among moles of reactants and products. For example, return to the reaction between iron and oxygen described in Table 12-1. The equation indicates that four moles of iron react with three moles of oxygen. It also indicates that four moles of iron react to produce two moles of iron(III) oxide. How many moles of oxygen react to produce two moles of iron(III) oxide You can use the relationships between coefficients to write conversion factors called mole ratios. A mole ratio is a ratio between the numbers of moles of any two substances in a balanced chemical equation. As another example, consider the reaction shown in Figure 12-2. Aluminum reacts with bromine to form aluminum bromide. Aluminum bromide is used as a catalyst to speed up a variety of chemical reactions. 

Balance an equation Use the oxidation-number method to balance the chemical equation for the SRB reaction. 

A balanced chemical equation must have the same number and types of atoms on both sides of the equation, and the sum of the electric charges must be the same for the reactants as for the products of the reaction. If all the reactants and products are known, the equation for a redox reaction may be balanced by the half-reaction method. (Another method, called the oxidation-number method, may also be used, but for our purposes knowledge of one method is sufficient.)... 

Oxidation numbers are useful in naming compounds, in writing formulas, and in balancing chemical equations. 

Chapter 7, Chemical Quantities and Reactions, introduces moles and molar masses of compounds, which are used in calculations to determine the mass or number of particles in a given quantity. Students leam to balance chemical equations and to recognize the types of chemical reactions combination, decomposition, single replacement, double replacement, and combustion reactions. Section 7.5 discusses Oxidation-Reduction Reactions using real-life examples, including biological reactions. Section... 

Balancing the chemical equation for a redox reaction by inspection can be a real challenge, especially for one taking place in aqueous solution, when water may participate and we must include HzO and either H+ or OH. In such cases, it is easier to simplify the equation by separating it into its reduction and oxidation half-reactions, balance the half-reactions separately, and then add them together to obtain the balanced equation for the overall reaction. When adding the equations for half-reactions, we match the number of electrons released by oxidation with the number used in reduction, because electrons are neither created nor destroyed in chemical reactions. The procedure is outlined in Toolbox 12.1 and illustrated in Examples 12.1 and 12.2. 

The oxidation state of an element in a compound is an indication of how many electrons each atom of that element has lost (positive oxidation state) or gained (negative). Since oxidation state is determined by a set of rules, rather than by experiment, its connection to the number of electrons actually transferred is rather tenuous. It is used in naming compounds and balancing some chemical equations. 

Oxidation numbers, sometimes called oxidation states, are signed numbers assigned to atoms in molecules and ions. They allow us to keep track of the electrons associated with each atom. Oxidation numbers are frequently used to write chemical formulas, to help us predict properties of compounds, and to help balance equations in which electrons are transferred. Knowledge of the oxidation state of an atom gives us an idea about its positive or negative character. In themselves, oxidation numbers have no physical meaning they are used to simplify tasks that are more difficult to accomplish without them. 

Once Pyro Valences have been assigned to all reactant species, we can proceed to balance an equation by the use of the concept that in a balanced equation, the sum of the oxidizing valences will equal the sum of the reducing valences, and the net, overall valence will be zero. This is the equivalent of saying that the number of electrons lost will equal the number of electrons gained—electrons are neither created nor destroyed, they just move from one atomic species to another during a chemical reaction. 

For the production of chemicals, the rate of the reaction is a key parameter for the productivity defined in Equation (5) as the number of molecules produced per time. In homogeneous systems, the reaction rate depends on temperature, pressure, and composition [1]. In the case of solarthermal cycles, a metal oxide is used for the C02-splitting reaction rendering the reaction medium a heterogeneous two-phase system consisting of a solid (metal, metal oxide) and a fluid (CO2, CO, or carrier gas with O2). Therefore, the reaction kinetics becomes much more complex. Whereas microscopic kinetics only deals with time-dependent progress of the reaction, macroscopic kinetics additionally takes the heat- and mass-transport phenomena in heterogeneous systems into account. The transfer of species from one phase to the other must be considered in the overall mass balance [1]. The reaction of a gas with a porous solid consists of seven steps ... 

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