Oxidation balancing equations

Water. Based on the overall balanced equation for this reaction, a minimum of one mole of water per mole of nitro compound is required for the reduction to take place. In practice, however, 4 to 5 moles of water per mole of nitro compound are used to ensure that enough water is present to convert all of the iron to the intermediate ferrous and ferric hydroxides. In some cases, much larger amounts of water are used to dissolve the amino compound and help separate it from the iron oxide sludge after the reaction is complete. 

With this as introduction, let us now look at the individual steps in more detail for the case of hydroboration-oxidation of 1-decene. A boron hydride that is often used is dibomne (B2H6). Diborane adds to 1-decene to give tridecylborane according to the balanced equation ... 

In earlier sections of this chapter, we showed how to write and balance equations for precipitation reactions (Section 4.2) and acid-base reactions (Section 4.3). In this section we will concentrate on balancing redox equations, given the identity of reactants and products. To do that, it is convenient to introduce a new concept, oxidation number. 

Before you can balance an overall redox equation, you have to be able to balance two halfequations, one for oxidation (electron loss) and one for reduction (electron gain). Sometimes that s easy. Given the oxidation half-equation... 

Throughout this discussion we will show balanced oxidation half-equations in yellow, balanced reduction half-equations in green.)... 

Write balanced equations for the reduction of each of the following oxide ores by carbon monoxide ... 

Of course, the oxidation number method gives the same balanced equation as the half-reaction method. 

By use of oxidation numbers, give a balanced equation for each of the following reactions ... 

In a similar manner, ethanol can be oxidized by the dichromate ion to form a compound called acetaldehyde, CHaCHO. The molecular structure of acetaldehyde, which is similar to that of formaldehyde, is shown at the bottom in Figure 18-6. We see that the molecule is structurally similar to formaldehyde. The methyl group, —CH3, replaces one of the hydrogens of formaldehyde. The balanced equation for the formation of acetaldehyde from ethanol is... 

Write the balanced equation for the production of pentanone from pentanol, using dichromate ion as the oxidizing agent. 

Chromic oxide, Cr,03, is used as a green pigment and is often made by the reaction between NajCrjOjfs) and NH(ClfsJ to give Cr >rfs), NaCl(s), Nifg), and HjO(g). Write a balanced equation and calculate how much pigment can be made from 1.0 X 101 kg of sodium dichromate. 

Cupric sulfide, copper(II) sulfide, reacts with hot nitric acid to produce nitric oxide gas, NO, and elemental sulfur. Only the oxidation numbers of S and N change. Write the balanced equation for the reaction. 

Write a balanced equation for the oxidation of pyruvic acid to CC and H20. 

H.9 In one stage in the commercial production of iron metal in a blast furnace, the iron(III) oxide, I c20 , reacts with carbon monoxide to form solid Fe 04 and carbon dioxide gas. In a second stage, the Fe304 reacts further with carbon monoxide to produce solid elemental iron and carbon dioxide. Write the balanced equation for each stage in the process. 

H.12 The reaction of boron trifluoride, BF,(g), with sodium borohydride, NaBH4(s), leads to the formation of sodium tetrafluoroborate, NaBF4(s), and diborane gas, B2Hfc(g). The diborane reacts with the oxygen in air, forming boron oxide, B20 j(s), and water. Write the two balanced equations leading to the formation of boron oxide. 

H.14 The compound Sb4OsCl2(s), which has been investigated because of its interesting electrical properties, can be prepared by warming a mixture of antimony(III) oxide and antimony(III) chloride, both of which are solids. Write a balanced equation for the reaction. 

H.17 The psychoactive drug sold as methampheramine ( speed ), CI0H,N, undergoes a series of reactions in the body the net result of these reactions is the oxidation of solid methamphetamine by oxygen gas to produce carbon dioxide gas, liquid water, and nitrogen gas. Write the balanced equation for this net reaction. 

H.20 The first stage in the production of nitric acid by the Ostwald process is the reaction of ammonia gas with oxygen gas, producing nitric oxide gas, NO, and liquid water. The nitric oxide further reacts with oxygen to produce nitrogen dioxide gas, which, when dissolved in water, produces nitric acid and nitric oxide. Write the three balanced equations that lead to the production of nitric acid. 

K.18 The industrial production of sodium metal and chlorine gas makes use of the Downs process, in which molten sodium chloride is electrolyzed (Chapter 12). Write a balanced equation for the production of the two elements from molten sodium chloride. Which element is produced by oxidation and which by reduction ... 

STRATEGY We expect a strongly negative value because all combustions are exothermic and this oxidation is like an incomplete combustion. First, add up the individual standard enthalpies of formation of the products, multiplying each value by the appropriate number of moles from the balanced equation. Remember that the standard enthalpy of formation of an element in its most stable form is zero. Then, calculate the total standard enthalpy of formation of the reactants in the same way and use Eq. 20 to calculate the standard reaction enthalpy. 

The key to writing and balancing equations for redox reactions is to think of the reduction and oxidation processes individually. We saw in Section K that oxidation is the loss of electrons and reduction the gain of electrons. 

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 compound P4S, is oxidized by nitrate ions in acid solution to give phosphoric acid, sulfate ions, and nitric oxide, NO. Write the balanced equation for each half-reaction and the overall equation for the reaction. 

When lcad(II) sulfide is treated with hydrogen peroxide, the possible products are either lead(II) sulfate or lead(IV) oxide and sulfur dioxide, (a) Write balanced equations for the two reactions, (b) Using data available in Appendix 2A, determine which possibility is more likely. 

Concentrated aqueous sulfuric acid, H2 SO4, is a strong oxidizing agent that can react with elemental carbon H2 SO4 + C CO2 + SO2 (unbalanced) What is the balanced equation for this process ... 

C21-0090. The first commercially successful method for the production of aluminum metal was developed in 1854 by H. Deville. The process relied on earlier work by the Danish scientist H. Oersted, who discovered that aluminum chloride is produced when chlorine gas is passed over hot aluminum oxide. Deville found that aluminum chloride reacts with sodium metal to give aluminum metal. Write balanced equations for these two reactions. 

If you know the reactants and products of a chemical reaction, you should be able to write an equation for the reaction and balance it. In writing the equation, first write down the correct formulas for all reactants and products. After they are written down, only then start to balance the equation. Do not balance the equation by changing the formulas of the substances involved. For simple equations, you should balance the equation by inspection. (Balancing oxidation-reduction equations will be presented in Chap. 13.) The following rules will help you to balance simple equations. 

In Sec. 13.2 we will learn to determine oxidation numbers from the formulas of compounds and ions. We will learn how to assign oxidation numbers from electron dot diagrams and more quickly from a short set of rules. We use these oxidation numbers for naming the compounds or ions (Chap. 6 and Sec. 13.4) and to balance equations for oxidation-reduction reactions (Sec. 13.5). In Sec. 13.3 we will learn to predict oxidation numbers for the elements from their positions in the periodic table in order to be able to predict formulas for their compounds and ions. 

One of the most important uses of oxidation numbers is in balancing redox (oxidation-reduction) equations. These equations can get very complicated, and a systematic method of balancing them is essential. There are many such methods, however, and each textbook seems to use its own. There are many similarities among the methods, however, and the following discussion will help no matter what method your instructor and your textbook use. 

Eqs. (19) and (20) were derived applying the steady-state approximation to the oxidized Fe-TAML species and using the mass balance equation [Fe-TAML] = 1 + [oxidized Fe-TAML] ([Fe-TAML] is the total concentration of all iron species, which is significantly lower than the concentrations of H2O2 and ED). The oxidation of ruthenium dye 8 is a zeroth-order reaction in 8. This implies that n[ED] i+ [H202]( i+ m). Eq. (19) becomes very simple, i.e.,... 

Balanced equations oxidation of sucrose Ci2H220n(s) + 1202 (g) —> 12C02(g) + 1 lH20(g)... 

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