Solubility guidelines

Compounds with water solubilities of less than 0.01 mol P1 are generally considered insoluble. MCAT will not require you to memorize the solubilities of different compounds. Nevertheless, here are a few solubility guidelines for compounds in water  

It is very unlikely tltat an MCAT question Nearly all ionic compounds containing nitrate (NO-T), ammonium (NH/), and al-tfOiircf require that you know these kali metals (Li+, Na, K+...) are soluble. solubilities. However, knowing them will 

Sulfate compounds (SO/-) are soluble, EXCEPT for mercury, lead, and the heavier alkaline metals (Hg,P Pbp Cap Sip Bap- 

Compounds containing the heavier alkaline metals (Cap Srp Bap are soluble when paired with sulfides (S2-) and hydroxides (OH ). 

Carbonates, phosphates, sulfides, and hydroxides (CO/, PO/, . SP OH ) are generally insoluble other than in the cases mentioned above. 

A substance is considered soluble if more than three grams of the substance dissolves in 100 ml of water. The more common rules are listed below. 1. All common salts of the group 1A elements and ammonium ions are soluble. 2. All common acetates and nitrates are soluble. 3. All binary compounds of group 7A elements (other than F) with metals are soluble except those of silver, mercury(l), and lead. 4. All sulfates are soluble except those of barium, strontium, lead, calcium, silver, and mercury(l). 5. Except for those in Rule 1, carbonates, hydroxides, oxides, sulfides, and phosphates are insoluble.  

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We could again apply the seven-step process in detail. Instead, we take a more compact approach. Begin by determining what species are present in the reaction mixture. Next, use the solubility guidelines to identify the precipitate. After writing the balanced net ionic reaction, use solution stoichiometry and a table of amounts to find the required quantities. 

The solubility guidelines can be used to design ways of making salts. Suppose that we want to prepare barium sulfate, BaSOq. This substance is opaque to X rays, so it is often used to visualize the intestinal tract. Patients are given a barium cocktail, and then the areas of interest are irradiated. Barium sulfate absorbs the X rays to give a picture of the intestines. Soluble barium salts are poisonous, but BaSOq is insoluble in water, so it can be administered safely. (Only 1.0 X 10" mol dissolves in 1 L ofwaterat25 °C.)... 

Sodium bromide and silver nitrate are both soluble ionic compounds, so the major species are Na , Ag, Br, NO3, and H3 O molecules. The solubility guidelines presented in Section 4- identify the... 

Refer to Section 6-8, Solubility Guidelines in Section 6-1, Table 6-4, and Examples 6-12 and 6-13. 

Refer to Sections 6-1 and 6-9, Exercise 6-89 and the Solubility Guidelines summarized in Table 6-4. ... 

Refer to Section 6-1 and the Solubility Guidelines summarized in Tables 6-4 and 6-5. 

How do you know which ionic compounds are soluble and which are not In your previous chemistry course, you learned a set of solubility guidelines. Table 9.3 summarizes these guidelines. Remember the higher guideline takes precedence. (For instance, guideline 3 says that carbonates have very low solubility. Sodium carbonate is soluble, however, because guideline 1 says that ionic compounds containing sodium are soluble.) Chemists do not usually work with solubility products for soluble compounds. Thus, you will not find soluble ionic compounds listed in tables. If you see a compound in a A p table, you know that it has a low solubility relative to compounds such as sodium chloride. 

The next Sample Problem shows how to predict whether or not a precipitate will form when two significant volumes of reactant are mixed together. You will need to use the solubility guidelines to decide whether or not an insoluble compound forms. 

Step 1 According to the solubility guidelines, NaF and Ca(N03)2 are both soluble, because ionic compounds that contain sodium or nitrate ions are soluble. When you mix the solutions, NaNOa, and CaFa can also form. NaNOa is soluble, but CaFa is not, according to guideline 4. 

Of the two possible products, the solubility guidelines predict that CdS, a sulfide, is insoluble and that NH4C1, an ammonium compound, is soluble. Thus, a precipitation reaction will occur ... 

A look at the solubility guidelines suggests that Cu(N03)2 and Na2C03 (among many other possibilities) might work ... 

Your answers to questions 7 and 8 represent a preliminary set of guidelines for predicting the solubility of the compounds you tested. Many reference books refer to guidelines like these as solubility rules. Why might solubility guidelines be a better term to use for describing solubility patterns ... 

You will be referring to the general solubility guidelines often in this chapter and in Chapter 10. They will help you identify salts that are soluble and insoluble in aqueous solutions. Always keep in mind, however, that water is a powerful solvent. Even an insoluble salt may dissolve enough to present a serious hazard if it is highly poisonous. 

Different references present solubility guidelines in different ways. During a 1 h "surf session" on the Internet, a student collected ten different versions. See how many versions you can find. 

This poem is by an unknown author. It is not great literature. For decades, however, it has helped many students remember the solubility guidelines. Maybe it will do the same for you. If not, you can try writing your own poem ... 

Start by identifying the ions in each pair of compounds. Then exchange the positive ions in the two compounds. Compare the resulting compounds against the solubility guidelines, and make your prediction. 

In this investigation, you will apply your knowledge of chemical reactions and the general solubility guidelines to identify unknown ions. 

Use the general solubility guidelines to name three reagents that will combine with each ion below to form a precipitate. Assume that the reactions take place in aqueous solution. For each reaction, write the net ionic equation. 

Recognize and classify acids (strong, weak), bases (strong, weak, insoluble), and salts (soluble, insoluble) use the solubility guidelines... 

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