BackSolubility Rules in Chemistry: Study Guide
Study Guide - Smart Notes
Tailored notes based on your materials, expanded with key definitions, examples, and context.
Solubility Rules
Introduction to Solubility
Solubility is a fundamental property that describes the ability of a solute to dissolve in a solvent. Understanding solubility rules is essential for predicting whether a compound will form a solution or a precipitate in water.
Soluble: Refers to a solute that can be dissolved when placed in a solvent.
Insoluble: Refers to a solute that cannot be dissolved when placed in a solvent.
Example: (AgBr is insoluble)
Example: (NaBr is soluble)
Solubility Rules Table
The solubility rules are a convenient set of guidelines to help determine if a compound will be soluble or insoluble in water. These rules are often summarized in tables and memory tools.
Soluble Compounds | Exceptions |
|---|---|
Alkali metals (Li+, Na+, K+, etc.) | None |
NH4+ (ammonium) | None |
NO3- (nitrate) | None |
ClO3- (chlorate) | None |
Cl-, Br-, I- (halides) | Ag+, Pb2+, Hg22+ |
SO42- (sulfate) | Ba2+, Sr2+, Pb2+, Ca2+ |
Memory Tool: The notes mention using GANA CASH for soluble ionic solutes and COPS for insoluble ionic solutes, with exceptions.
Insoluble Compounds Table
Insoluble Compounds | Exceptions |
|---|---|
CO32- (carbonate) | Alkali metals, NH4+ |
PO43- (phosphate) | Alkali metals, NH4+ |
SO32- (sulfite) | Alkali metals, NH4+ |
S2- (sulfide) | Alkali metals, NH4+ |
OH- (hydroxide) | Alkali metals, Ba2+, Sr2+, Ca2+ |
Examples and Applications
Example: How many ions will the following soluble compound produce: Na2SO4? Answer: Na2SO4 dissociates into 2 Na+ and 1 SO42-, for a total of 3 ions.
Example: According to the solubility rules, which of the following ionic compounds will be insoluble? Answer: BaSO4 (barium sulfate) is insoluble due to the sulfate exception for Ba2+.
Example: Based on the chart, which of the following substances will be soluble in water? Answer: Zn(NO3)2 is soluble because all nitrates are soluble.
Key Terms and Definitions
Solute: The substance being dissolved.
Solvent: The substance doing the dissolving (usually water in chemistry).
Precipitate: An insoluble solid formed from a reaction in solution.
Ionic Compound: A compound composed of positive and negative ions.
Additional Info
Solubility rules are essential for predicting the outcomes of double displacement reactions and for identifying precipitates in qualitative analysis.
Exceptions to the rules are important and often tested in exams.
