Acidic solution balancing redox equation

The following redox reactions occur in acidic solution. Balance the equations using the half-reaction method. 

There are some complications. As we know from Section 13.6, iron(III) ions tend to hydrolyze in aqueous solution unless the pH is very low. Accordingly, it is understood that, unless otherwise stated, E° values refer to measurements in 1.0 mold acid solution, even if the hydrogen ions do not explicitly appear in the balanced redox equation (e.g., reaction 15.12). Second, iodide ion actually reacts with iodine in water to give brown I3- ... 

The key to the oxidation-number method of balancing redox equations is to realize that the net change in the total of all oxidation numbers must be zero. That is, any increase in oxidation number for the oxidized atoms must be matched by a corresponding decrease in oxidation number for the reduced atoms. Take the reaction of potassium permanganate (KMn04) with sodium bromide in aqueous acid, for example. An aqueous acidic solution of the purple permanganate anion (Mn04 ) is reduced by Br- to yield the nearly colorless Mn2+ ion, while Br- is oxidized to Br2. The unbalanced net ionic equation for the process is... 

Equations for redox reactions are sometimes difficult to balance. Use the steps in Skills Toolkit 2 below to balance redox equations for reactions in acidic aqueous solution. An important step is to identify the key ions or molecules that contain atoms whose oxidation numbers change. These atoms are the starting points of the unbalanced half-reactions. For the reaction of zinc and hydrochloric acid, the unbalanced oxidation and reduction half-reactions would be as follows ... 

Compare and contrast balancing redox equations in acidic and basic solutions. 

By combining (i), (ii) and (iii) write a balanced equation for the redox reaction which occurs between MnUa and iron(ll) ethanedioate, FcCjO., (Fc and CjOa" ions in acid solution) above 60°C in acid solution. Use this equation to calculate the volume of a mangan-ate(VII) solution of eoncemration 0.0200 moldm required for... 

EXERCISE 20.2 Balancing Redox Equations in Acidic Solution... 

There are several ways to balance complicated redox equations. We have shown you only one, and that is only for acidic solutions. If your instructor prefers another method, by all means use it. Whatever method you use, it takes practice to perfect it You may question this while learning, but many students report that once they get the hang of it, balancing redox equations is fun ... 

In this section, each equation identifies an oxidizer and a reducer, as well as the oxidized and reduced products of the redox reaction. Write separate oxidation and reduction half-reaction equations, assuming that the reaction takes place in an acidic solution, and add them to produce a balanced redox equation. 

The activity series enables us to predict whether or not a metal will be oxidized by a solution containing a particular salt or by an acid. Sample Problems 4.7 and 4.8 give you more practice making such predictions and balancing redox equations. 

Write the balanced half-reactions and a balanced redox equation for each of the following reactions in acidic solution (15.3)... 

Briefly describe (a) half-equation method of balancing redox equations (b) disproportionation reaction (c) titration (d) standardization of a solution. Explain the important distinctions between (a) a strong electrolyte and strong acid (b) an oxidizing agent and reducing agent (c) precipitation reactions and neutralization reactions (d) half-reaction and overall reaction. 

EXAMPLE 12.1 Sample exercise Balancing a redox equation in acidic solution... 

An alternative to the oxidation-number method for balancing redox reactions is the half-reaction method. The key to this method is to realize that the overall reaction can be broken into two parts, or half-reactions. One half-reaction describes the oxidation part of the process, and the other half-reaction describes the reduction part. Each half is balanced separately, and the two halves are then added to obtain the final equation. Let s look at the reaction of aqueous potassium dichromate (K2Cr2C>7) with aqueous NaCl to see how the method works. The reaction occurs in acidic solution according to the unbalanced net ionic equation... 

The following redox reaction occurs in an acidic solution Ce4 + Bi — Ce3+ + Bi01+. What is the coefficient before the C e4 when the equation is fully balanced ... 

Using half-reactions, balance the equation for the redox reaction when Cr207 (fl ) and Fe " (fl ) react to form Cr " (a ) and Fe " (fl ) in acidic solution. 

In this case, the hydrogen ion and the water molecule are eliminated because neither is oxidized nor reduced. The only additional information needed is that the reaction takes place in acid solution. In acid solution, hydrogen ions (H+) and water molecules are abundant and free to participate in redox reactions as either reactants or products. Some redox reactions can occur only in basic solution. When you balance equations for these reactions, you may add hydroxide ions (OH ) and water molecules to either side of the equation. Basic solutions have an abundance of OH ions instead of H30" ions. 

Use the oxidation-number method to balance this net ionic redox equation for the reaction between the perchlorate ion and the bromide ion in acid solution. 

Calculating The concentration of thallium(I) ions in solution may be determined by oxidizing to thallium(III) ions with an aqueous solution of potassium permanganate (KMn04) under acidic conditions. Suppose that a 100.00 mL sample of a solution of unknown T1+ concentration is titrated to the endpoint with 28.23 mL of a 0.0560M solution of potassium permanganate. What is the concentration of T1+ ions in the sample You must first balance the redox equation for the reaction to determine its stoichiometry. 

Before you attempt to balance the equation for a redox reaction, why do you need to know whether the reaction takes place in acidic or basic solution (20.3)... 

Use the half-reaction method to balance these equations for redox reactions. Add water molecules and hydrogen ions (in acid solutions) or hydroxide ions (in basic solutions) as needed. 

An alternative procedure for basic solutions is to balance the redox equation for acid solutions first. Then, add... 

Balancing Redox Reactions in Acidic Solution When a redox reaction occurs in acidic solution, H2O molecules and ions are available for balancing. Even though we ve usually used H30 to indicate the proton in water, we use H" in this chapter because it makes the balanced equations less complex. 

Balancing Redox Reactions in Basic Solution As you just saw, in acidic solution, H2O molecules and H ions are available for balancing. As Sample Problem 21.1 shows, in basic solution, H2O molecules and 0H ions are available. Only one additional step is needed to balance a redox equation that takes place... 

Balance a Net Ionic Redox Equation Balance the following redox equation. CI04 (aq) + Br (aq) —> Ch(aq) + Br2(g) (in acid solution)... 

Solve Potassium permanganate oxidizes chloride ions to chlorine gas. Balance the equation for this redox reaction taking place in acid solution. 

The redox reaction between dichromate ion and iodide ion in acid solution is shown in Figure 19.15. Use the half-reaction method to balance the equation for this redox reaction. 

Problem 8.12. The breatholyzer test for blood alcohol requires breathing into a tube containing a gel impregnated with an acidic solution of potassium dichromate. Alcohol in the breath will be oxidized to CO2, and the yellow dichromate will be reduced to the green chromium(III) ion. Balance the following equation which represents the redox process ... 

When an aqueous solution of iron(III) ions is reacted with sulfur dioxide gas (this forms an acid solution), aqueous iron(II) ions and the sulfate ion (SO ) are produced. Write a balanced overall redox equation for the reaction. 

Analyze We are given an incomplete, unbalanced (skeleton) equation for a redox reaction occurring in acidic solution and asked to complete and balance it. 

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