use the solubility rules to explain why Mg(OH)2 is a weak base Solution In order

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In order to know which species to split up (dissociate), you must have a working knowledge of basic solubility rules. Here's an abbreviated list. 1. All common compounds of Group I and ammonium ions are soluble. 2. All nitrates, acetates, and chlorates are soluble. 3. All binary compounds of the halogens (other than F) with metals are soluble, except those of Ag, Hg(I), and Pb. Pb halides are soluble in hot water.) 4. All sulfates are soluble, except those of barium, strontium, calcium, lead, silver, and mercury (I). The latter three are slightly soluble. 5. Except for rule 1, carbonates, oxides, silicates, and phosphates are insoluble. 6. Sulfides are insoluble except for calcium, barium, strontium, magnesium, sodium, potassium, and ammonium. 7. Hydroxides are insoluble except for Rule 1 and the Group II elements other than Mg. The table that you referenced in your question contains only insoluble compounds so it has limited use. It's better to know the rules. Step 1. AgNO3 + NaCl ==> AgCl + NaNO3 Step 2. Which of the species will dissociate? AgNO3 is a nitrate salt and Rule 2 above says that all nitrates are soluble. So we split it. NaCl (table salt) contains Na+ and all Na+ salts are soluble (Rule 1). AgCl ... in Rule 3, all binary (two-element) compounds of the non-fluorine halogens (Cl, Br, I) are soluble EXCEPT those of Ag, Hg(I), and Pb(II). So AgCl does NOT get split. NaNO3 is another Na+ and NO3- salt so it gets split. Step 3: Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) ==> AgCl(s) + Na+(aq) + NO3-(aq) Step 4: Cross out the spectator ions which appear on both sides (NO3- and Na+). Ag+(aq) + Cl-(aq) ==> AgCl(s) Basically, you split up anything labeled (aq) UNLESS that species is a weak acid (like acetic acid) or a weak base (like NH3). You also NEVER split pure liquids and gases like H2O(l) or CO2(g). Another one... Step 1. 2HC2H3O2 + Ba(OH)2 ==> Ba(C2H3O2)2 + 2H2O Step 2. HC2H3O2 (acetic acid) is a WEAK acid so we do NOT split it. Most hydroxides are insoluble, but Ba(OH)2 is (Rule 7) so we split it. Ba(C2H3O2)2 is soluble (Rule 2 regrading acetates) and H2O is a pure liquid (NO splitting). Step 3. 2HC2H3O2(aq) + Ba2+(aq) + 2OH-(aq) ==> Ba2+(aq) + 2C2H3O2-(aq) + 2H2O(l) Step 4. The only spectator ion is Ba2+(aq). 2HC2H3O2(aq) + 2OH-(aq) ==> 2C2H3O2-(aq) + 2H2O(l)

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