sr_dr_reactions.notebook
March 27, 2017
Using the Solubility Rules (p. 6 of Reference Tables)
­ the left column shows all ionic compounds that are soluble in water
­this means they will dissolve and form ions
­label them as aqueous (aq)
­exceptions are NOT aqueous, they do not dissolve
­ label
them solid (s)
Practice: label each (aq) or (s)
1. Ba(NO3)2
2. PbCl2
3. NaF
4. Na2SO4
5. BaSO4
­ the right column shows all ionic compounds that are NOT soluble
in water
­this means they will NOT dissolve and will NOT form ions
­label them as solid (s)
­exceptions are aqueous, they DO dissolve
­ label them aqueous (aq)
Practice: label each (aq) or (s)
1. CaCO3
2. Na2CO3
3. NaOH
4. Ca(OH)2
5. CuS
1
sr_dr_reactions.notebook
March 27, 2017
• In a double replacement reaction, one of the products must be insoluble in water in order for the reaction to take place
> insoluble means it does not dissolve in water ­ a solid is formed (called a precipitate)
> if neither of the products are insoluble, the ions just stay in the aqueous solution and don't interact with each other
• A net ionic equation only shows the ions that were used to make the precipitate.
• Some ions were always dissolved in water. These are called “spectator ions”. (They don’t do anything, so we can ignore them.)
• Steps for Writing a Complete and Net Ionic Equation:
> Complete Ionic Equation (shows all ions): – separate all "aqueous" species into ions « subscripts that aren't part of the formula of a polyatomic ion tell you how many ions are in the formula unit
« don't forget to multiply by the coefficient!
« label these ions with the charge and (aq)
– anything that is a solid (s) remains whole and unchanged
– the equation should balance ­ double­check
> Net Ionic Equation: – cross out the spectator ions « spectators are ions that are unchanged as you go from the reactants to the products
– write what is left – if all species are aqueous and all ions cancel, write "No reaction, all aqueous"
Example: CaCl2 (aq) + 2AgNO3 (aq) à Ca(NO3)2 (aq) + 2AgCl (s)
2
sr_dr_reactions.notebook
March 27, 2017
3
sr_dr_reactions.notebook
March 27, 2017
4
sr_dr_reactions.notebook
March 27, 2017
5
sr_dr_reactions.notebook
March 27, 2017
Now you can predict the products and determine if the reaction
will occur:
To write the complete and net ionic equations…
1. Write formulas* of reactants and use solubility rules to determine state (aq or s)
2. Determine the products (switch the positive ions)
­write formulas* and use solubility rules to determine state (aq or s)
*don’t forget to use the periodic table and list of polyatomic ions to determine charge
3. Balance equation (this is a balanced chemical equation)
4. Split anything that is aq into ions
­leave the s alone
(this is the complete ionic equation)
5. Cross out spectator ions
6. Write what is left (this is the net ionic equation)
K2CO3 (aq) + Ba(NO3)2 (aq) à 6
sr_dr_reactions.notebook
March 27, 2017
7
sr_dr_reactions.notebook
March 27, 2017
8