How to Memorize the Solubility Rules for Common Ionic Compounds in Water
Recognize that salts containing Group 1A elements are soluble., Know that salts containing nitrates, chlorates, and acetates are soluble., Understand that all ammonium salts are soluble., Know that most hydroxide compounds are insoluble., Recognize...
Step-by-Step Guide
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Step 1: Recognize that salts containing Group 1A elements are soluble.
The periodic table is organized into rows and columns called periods and groups, respectively.
The first column of the table contains the Group 1A elements.
They are the alkali metals and include Li, Na, K, Cs, and Rb.For example:
KCl and LiOH are soluble in water. -
Step 2: Know that salts containing nitrates
When a nitrate, NO3-, chlorate, ClO3-, or acetate, CH3COO-, form a salt, they are soluble in water.For example:
KNO3, NaClO3, and CH3COONa are all soluble., The ammonium ion, NH4+, makes salt compounds that completely dissociate in the presence of water.
There are no exceptions to this rule.For example:
NH4OH is soluble even though it contains a hydroxide. , Some hydroxide salts are slightly soluble: hydroxides formed with Group 2 elements (Ca, Sr, and Ba).
The exception to this rule is that hydroxide salts formed with Group 1 elements are soluble because Group 1A elements are always soluble.For example:
Fe(OH)3, Al(OH)3, and Co(OH)2 are insoluble, but LiOH and NaOH are soluble. , Group 17 nonmetals include chlorine (Cl-), bromine (Br-), and iodine (I-).
Exceptions to this rule include silver, lead, and mercury.
Compounds consisting of these nonmetals and ions are not soluble.For example:
AgCl and Hg2Cl2 are both insoluble.
Note that PbCl2, PbBr2, and PbI2 are soluble in HOT water., The chemical formulas for each of these are as follows:
CO3 (carbonates), CrO4 (chromates), and PO4 (phosphates).
Exceptions to this rule include the Group 1A metals and NH4+ compounds which are soluble.
For example:
Compounds like CaCO3, PbCrO4, and Ag3PO4 are all insoluble while compounds like Na3PO4 and (NH4)2CO3 are soluble. , Most of the salt compounds containing SO4 are soluble in water.
Exceptions to this rule include the following ions Ca+2, Ba+2, Pb+2, Ag+, Sr+2, and Hg+2.
Sulfate salts containing these ions are insoluble.For example:
Na2SO4 is completely soluble, but CaSO4 and BaSO4 are not soluble., As with many of the other rules, there are exceptions including barium, calcium, magnesium, sodium, potassium, and ammonium.
Only sulfide compounds made with these elements are soluble in water.For example:
CdS, FeS, and ZnS are all insoluble. -
Step 3: chlorates
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Step 4: and acetates are soluble.
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Step 5: Understand that all ammonium salts are soluble.
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Step 6: Know that most hydroxide compounds are insoluble.
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Step 7: Recognize that salts containing Group 17 nonmetals are generally soluble.
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Step 8: Know that most carbonates
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Step 9: chromates
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Step 10: and phosphates are insoluble.
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Step 11: Understand that most sulfate salts are soluble.
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Step 12: Recognize that most sulfides are insoluble in water.
Detailed Guide
The periodic table is organized into rows and columns called periods and groups, respectively.
The first column of the table contains the Group 1A elements.
They are the alkali metals and include Li, Na, K, Cs, and Rb.For example:
KCl and LiOH are soluble in water.
When a nitrate, NO3-, chlorate, ClO3-, or acetate, CH3COO-, form a salt, they are soluble in water.For example:
KNO3, NaClO3, and CH3COONa are all soluble., The ammonium ion, NH4+, makes salt compounds that completely dissociate in the presence of water.
There are no exceptions to this rule.For example:
NH4OH is soluble even though it contains a hydroxide. , Some hydroxide salts are slightly soluble: hydroxides formed with Group 2 elements (Ca, Sr, and Ba).
The exception to this rule is that hydroxide salts formed with Group 1 elements are soluble because Group 1A elements are always soluble.For example:
Fe(OH)3, Al(OH)3, and Co(OH)2 are insoluble, but LiOH and NaOH are soluble. , Group 17 nonmetals include chlorine (Cl-), bromine (Br-), and iodine (I-).
Exceptions to this rule include silver, lead, and mercury.
Compounds consisting of these nonmetals and ions are not soluble.For example:
AgCl and Hg2Cl2 are both insoluble.
Note that PbCl2, PbBr2, and PbI2 are soluble in HOT water., The chemical formulas for each of these are as follows:
CO3 (carbonates), CrO4 (chromates), and PO4 (phosphates).
Exceptions to this rule include the Group 1A metals and NH4+ compounds which are soluble.
For example:
Compounds like CaCO3, PbCrO4, and Ag3PO4 are all insoluble while compounds like Na3PO4 and (NH4)2CO3 are soluble. , Most of the salt compounds containing SO4 are soluble in water.
Exceptions to this rule include the following ions Ca+2, Ba+2, Pb+2, Ag+, Sr+2, and Hg+2.
Sulfate salts containing these ions are insoluble.For example:
Na2SO4 is completely soluble, but CaSO4 and BaSO4 are not soluble., As with many of the other rules, there are exceptions including barium, calcium, magnesium, sodium, potassium, and ammonium.
Only sulfide compounds made with these elements are soluble in water.For example:
CdS, FeS, and ZnS are all insoluble.
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