Ion Concentration

Dissociation: 
Ionic compounds are made up of two parts:

• Cation: Positively charged particle 
• Anion: Negatively charged particle 

In a process called dissociation, shown in the video below, the cation and anion in an ionic compound separate from each other.  

Dissociation can be written in a dissociation equation, in which the atoms and charges must balance. The format for such an equation is AB => A + B. Knowing this, we can write the dissociation of the Sodium Chloride from the above video as: 

• NaCl => Na⁺ + Cl^-    

Example One:  

• BaSO4 => Ba ²⁺ + SO4 ^2-  
• (NH4)2CO3 => 2NH4 ⁺ + CO3 ^2-   
• Al2(SO4)3 => 2Al³⁺ + 3SO4 ^2-   

Example Two:  

Determine each of the ion concentrations when a 4.52 M solution of Ammonium Nitrate dissociates.  

• NH4NO3 => NH4 ⁺ + NO3 ^-   

•  4.52 M x (1/1) = 4.52 M 
•                          = [NH4 ⁺] 
•                          = [NO3 ^-] 

Determine each of the ion concentrations when a 0.56 M solution of Iron (III) Hydroxide dissociates.  

• Fe(OH)3 => Fe ³⁺ + 3OH ^-   

•  0.56 M x (1/3) = 0.19 M 
•                          = [Fe ³⁺] 
•  0.56 M x (3/1) = 1.68 M  
•                          = [OH ^- ]  

-Simon Sierra