Aqueous ionic reactions spectator ions

The K+ andN03 ions remain unchanged in aqueous solution as spectator ions . All ions involved in the reaction must be represented in the ionic equation. 

Figure 4.4 An aqueous ionic reaction and its equations. When silver nitrate and sodium chromate solutions are mixed, a reaction occurs that forms solid silver chromate and a solution of sodium nitrate. The photos present the macroscopic view of the reaction, the view the chemist sees in the lab. The blow-up arrows lead to an atomic-scale view, a representation of the chemist s mental picture of the reactants and products. (The pale ions are spectator ions, present for electrical neutrality, but not involved in the reaction.) Three equations represent the reaction in symbols. (The ions that are reacting are shown in red type.) The molecular equation shows all substances intact. The total Ionic equation shows all soluble substances as separate, solvated ions. The net Ionic equation eliminates the spectator ions to show only the reacting species.

A molecular equation for an aqueous ionic reaction shows undissociated substances. A total Ionic equation shows all soluble Ionic compounds as separate, solvated ions. Spectator ions appear unchanged on both sides of the equation. By eliminating them, you see the actual chemical change in a net ionic equation. 

To describe an aqueous ionic reaction, chemists use a net ionic equation because it eliminates spectator ions (those not involved in the reaction) and shows the actual chemical change taking place. 

A net ionic equation for a reaction in aqueous solution includes only compounds and ions that change chemically in the reaction. Spectator ions are ions that do not take part in such a reaction. 

C04-0107. A white precipitate forms when aqueous calcium nitrate is mixed with aqueous ammonium sulfate, (a) Identify the precipitate and write the net ionic equation for the reaction, (b) What are the spectator ions ... 

With all the possible equilibria in aqueous systems, most species might be expected to participate in at least one equilibrium. Nonetheless, in many solutions some of the ionic species undergo no significant reactions. These species are classified as spectator ions. 

This net ionic equation focuses only on the substances that are actually involved in the reaction. It indicates that an aqueous solution containing Pb2+ (any solution, not just Pb(N03)2(aq)) will react with any solution containing the sulfate ion to form insoluble lead(II) sulfate. If this equation form is used, the spectator ions involved will not be known, but in most cases this is not a particular problem since the focus is really the general reaction, and not the specific one. You will be expected to write the balanced net ionic equation for many of the reactions on the test. 

Write balanced half-reactions from the net ionic equation for the reaction between solid aluminum and aqueous iron(in) sulfate. The sulfate ions are spectator ions, and are not included. 

Chemistry is often conducted in aqueous solutions. Soluble ionic compounds dissolve into their component ions, and these ions can react to form new products. In these kinds of reactions, sometimes only the cation or anion of a dissolved compound reacts. The other ion merely watches the whole affair, twiddling its charged thumbs in electrostatic boredom. These uninvolved ions cire called spectator ions. 

Hydrogen bromide is a strong acid whose aqueous solution contains H + ions and Br -ions. Barium hydroxide is a strong base whose aqueous solution contains Ba2+ and OH " ions. Thus, we have a mixture of four different ions on the reactant side. Write the neutralization reaction as an ionic equation, and then cancel spectator ions to give the net ionic equation. 

There are three important classes of aqueous reactions. Precipitation reactions occur when solutions of two ionic substances are mixed and a precipitate falls from solution. To predict whether a precipitate will form, you must know the solubility of each potential product. Acid-base neutralization reactions occur when an acid is mixed with a base, yielding water and a salt. The neutralization of a strong acid with a strong base can be written as a net ionic equation, in which nonparticipating, spectator ions are not specified ... 

A chemical reaction occurs when the following aqueous solutions are mixed sodium sulfide and iron(II) sulfate. Identify the spectator ions. Then write the balanced net ionic equation. 

Q C99 State the name and formula of the precipitate that forms when aqueous solutions of copper(II) sulfate and sodium carbonate are mixed. Write the net ionic equation for the reaction. Identify the spectator ions. 

Identify spectator ions and write net ionic equations for reactions in aqueous solutions. 

When two solutions are mixed, all of the ions are present in the combined solution. In many cases, some of the ions will react with each other. However, some ions do not react. These spectator ions remain unchanged in the solution as aqueous ions. In the equation above, the K" and NO3 ions appear as aqueous ions both on the reactants side and on the products side. Because K" and NO3 ions are spectator ions in the above reaction, they can be removed from the total ionic equation. What remains are the substances that do change during the reaction. 

Figure 4.8 An aqueous strong acid-strong base reaction on the atomic scale. When solutions of a strong acid (HX) and a strong base (MOH) are mixed, the HaO from the acid transfers a proton to the OH from the base to form an H2O molecule. Evaporation of the water leaves the spectator ions, X and M, as a solid ionic compound called a salt...

You are given the word equation for the reaction that occurs between hydrochloric acid and aqueous lithium hydroxide to produce water and aqueous lithium chloride. You must determine the chemical formulas for and relative amounts of all reactants and products to write the balanced chemical equation. To write the complete ionic equation, you need to show the ionic states of the reactants and products. By crossing out the spectator ions from the complete ionic equation, you can write the net ionic equation. 

The molecular and total ionic equations above show that if you evaporate the water, the spectator ions remain the ionic compound that results from the reaction of an acid and a base is called a salt, which in this case is barium chloride. Thus, in an aqueous neutralization reaction, an acid and a base form a salt solution and water ... 

Just one more example before we move on to the next chapter. An aqueous solution of FeClj is yellow. An aqueous solution of NaOH is colorless. If we mix the two solutions together, we get a rusty brown precipitate. We know from rule 1 that NaCl is soluble. Rule 6 tells us that FeCOHJj is insoluble. Therefore, in this reaction Na+ and Cl are spectator ions and the precipitate is Fe(OH)3. This reaction is shown in the following net ionic equation ... 

A third representation of an aqueous reaction is the net ionic equation, in which the spectator ions—those that do not change in the course of the reaction—are left out of the equation. 

An ionic equation is simpler than a full chemical equation. It shows only the ions or other particles that are reacting. Spectator ions are omitted. Compare the full equation for the reaction of zinc with aqueous copper(II) sulfate with the ionic equation. 

The aqueous nitrate ions can be left out to produce the ionic equation they are spectator ions that do not get involved in the reaction ... 

Reactions that form water or a gas Some double-replacement reactions in aqueous solution produce water or a gas (or both) rather than a precipitate. In such cases, the water or gas is shown as a product in the net ionic equation, as are the ions that produced it. The remaining ions are eUminated as spectator ions. The following example problem illustrates this concept. 

As we demonstrated in the case of displacement reactions, it is possible to write the equation involving compounds that dissociate. It consists in dissociating all aqueous compounds into their respective ions and leaving solids as they are. This constitutes the complete ionic equation. Common ions that appear in both reactants and products will cancel each other out they are spectator ions. The resulting equation is the net ionic equation. 

Precipitation Reactions—Some reactions in aqueous solution involve the combination of ions to yield a water-insoluble solid—a precipitate. Precipitation reactions are generally represented by net ionic equations, a form in which only the reacting ions and solid precipitates are shown, and spectator ions are deleted. Precipitation reactions usually can be predicted by using a few simple solubility guidelines (Table 5.1). 

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