Ion Concentration

Dissociation
- Ionic compound are made up of two parts (metal+non-metal)
   -Cation: positively charged particle
   -Anion: negatively charged particle

• When ionic compounds are dissolved in water, the cation and anion separate from each other
• This process is called dissociation
• When writing dissociation equation the atoms and charges must balance

The dissociation of Sodium Chloride is:

NaCl(s)-----> Na+(aq)+Cl-(aq)

Fe(OH)2----> Fe^2+ 2OH-

Na3(PO4)2--> 3Na+ + PO4^-3

Fe3 (PO4)2---> 3Fe^-2 + 2PO4^-3

If the volume does not change then the concentration of individual ions depends on the balanced coefficients in the dissociation equation.

Determine the [Na+] and [PO4^-3] in a 1.5 M solution of Na3PO4

Na3Po4---> 3Na+ + PO4^-3

1.5M                          1.5M

1.5M x 3/1 (need/have) = 4.5 [Na+]

Lithium Sulphate:

Li2^+O4^-2 ----> 2Li+ + SO4

2.5M                    5M        2.5M

For Lithium, it is 2.5 M x (need/have) 2/1 = 5M

SO4, it is 2.5 M x (need/have) 1/1= 2.5M

http://www.youtube.com/watch?v=_vulYxwVFbA

http://www.youtube.com/watch?v=aZKIeFiOP34

BY KRYSTA DEL ROSARIO :D