Describing Reactions in Aqueous Solutions

Predict whether a solid will form when the following pairs of solutions are mixed. If so, identify the solid and write the balanced equation for the reaction. 

A strong electrolyte is a substance that completely breaks apart into ions when dissolved in water. The resulting solution readily conducts an electric current. 

Much important chemistry, including virtually all of the reactions that make life possible, occurs in aqueous solutions. We will now consider the types of equations used to represent reactions that occur in water. For example, as we saw earlier, when we mix aqueous potassium chromate with aqueous barium nitrate, a reaction occurs to form solid barium chromate and dissolved potassium nitrate. One way to represent this reaction is by the equation 

This is called the molecular equation for the reaction it shows the complete formulas of all reactants and products. However, although this equation shows the reactants and products of the reaction, it does not give a very clear picture of what actually occurs in solution. As we have seen, aqueous solutions of potassium chromate, barium nitrate, and potassium nitrate contain the individual ions, not molecules as is implied by the molecular equation. Thus the complete ionic equation, 

The complete ionic equation reveals that only some of the ions participate in the reaction. Notice that the and N03 ions are present in solution both before and after the reaction. Ions such as these, which do not participate directly in a reaction in solution, are called spectator ions. The ions that participate in this reaction are the Ba and Cr04 ions, which combine to form solid BaCr04  

To learn to describe reactions in solutions by writing molecular, complete ionic, and net ionic equations. 

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In Chapter 2 we studied composition stoichiometry, the quantitative relationships among elements in compounds. In this chapter as we study reaction stoichiometry— the quantitative relationships among substances as they participate in chemical reactions—we ask several important questions. How can we describe the reaction of one substance with another How much of one substance reacts with a given amount of another substance Which reactant determines the amounts of products formed in a chemical reaction How can we describe reactions in aqueous solutions ... 

Describe reactions in aqueous solutions by writing formula unit equations, total ionic equations, and net ionic equations... 

Let us first look at how we write chemical equations that describe reactions in aqueous solutions. We use three kinds of chemical equations. Table 4-9 shows the kinds of information about each substance that we use in writing equations for reactions in aqueous... 

Describing Reactions in Aqueous Solutions 1 83 / Self-Check Exercise 7.1... 

Patents for his process were issued to Griesheim-Electron in 1912/1913. They described a mercuric chloride catalyst supported on coke or pumice. The early catalysts described in 1912 could only operate for short periods because mercury compounds sublime at reaction temperature. Although the 1913 patent described reaction in aqueous solution with the mercuric chloride catalyst, this process was never used industrially. A further patent in 1913 claimed that the process only took place in the presence of the mercury catalyst that accelerated the reaction. ... 

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