Net Ionic Equations

Equations attempt to show only

the exact particles involved in the

reaction.

Net Ionic Equations

You must first decide - are

substances written as molecules

or ions?

Net Ionic Equations

(NH4)2S + Fe(NO3)2 2NH4NO3 + FeS

This is a molecular equation.

(NH4)2S + Fe(NO3)2 2NH4NO3 + FeS

S-2 + Fe+2 FeS

This is the same equation

written in net ionic form.

Write this in net ionic form:

H2SO4(aq) H2O(l) + SO3(aq)

Which are molecules?

Which are ions?

Seven rules to help you decide ionsSeven rules to help you decide ions

or molecules.or molecules.

Rule #1 - Binary acidsRule #1 - Binary acids

Strong Acids are written in ionic form.Strong Acids are written in ionic form.

Examples: HCl, HBr, HI Examples: HCl, HBr, HI

Weak Acids are written in molecular form.Weak Acids are written in molecular form.

Examples: All Others Examples: All Others

Rule #2 - Ternary acidsRule #2 - Ternary acids

Strong Ternary Acids: Strong Ternary Acids: the number of oxygen atoms the number of oxygen atoms exceeds the number of hydrogen exceeds the number of hydrogen atoms by two or more, are written atoms by two or more, are written in ionic form. in ionic form.

Examples: HExamples: H22SOSO44, HNO, HNO33

Weak ternary acids are written Weak ternary acids are written in molecular form.in molecular form.

Examples: HExamples: H33POPO44

Rule #2 - Ternary acidsRule #2 - Ternary acids

Rule #3 - Polyprotic acidsRule #3 - Polyprotic acids

Those acids have more than oneThose acids have more than one

ionizable hydrogen atom. ionizable hydrogen atom.

The first hydrogen is ionized. The first hydrogen is ionized.

The second and all other ionizations are The second and all other ionizations are

always weak.always weak.

Rule #4 - BasesRule #4 - Bases

Hydroxides of Groups (IA) and (IIA),Hydroxides of Groups (IA) and (IIA),

except Be, are strong bases andexcept Be, are strong bases and

written in ionic form. written in ionic form.

All others are weak bases and written All others are weak bases and written

in molecular form.in molecular form.

Rule #5 - SaltsRule #5 - Salts

Salts are written in molecular Salts are written in molecular

form if they are insoluble. form if they are insoluble.

Salts are written in ionic form ifSalts are written in ionic form if

they are soluble.they are soluble.

Salt Solubility RulesSalt Solubility Rules

Salts of Group (IA) and ammonia areSalts of Group (IA) and ammonia aresoluble. soluble.

Acetates and nitrates are soluble.Acetates and nitrates are soluble.

Binary compounds of Group (VIIA),Binary compounds of Group (VIIA),except F, with metals, except Ag, Hgexcept F, with metals, except Ag, Hg+1+1,,and Pb, are solubland Pb, are soluble.e.

All sulfates are soluble, except those ofAll sulfates are soluble, except those of

Ba, Sr, Pb, Ca, Ag, and HgBa, Sr, Pb, Ca, Ag, and Hg+1+1. .

Except for those in Rule 1, carbonates,Except for those in Rule 1, carbonates,

hydroxides, oxides, sulfides, andhydroxides, oxides, sulfides, and

phosphates are insoluble.phosphates are insoluble.

Salt Solubility RulesSalt Solubility Rules

Rule #6 - oxidesRule #6 - oxides

Oxides are always written inOxides are always written in

molecular form.molecular form.

Rule #7 - gasesRule #7 - gases

Gases are always written inGases are always written in

molecular form.molecular form.





molecule or ion?

Which Rule?



H+(aq) + HSO4

-(aq)



H+(aq) + HSO4

-(aq) molecule

or ion?Which Rule?



H+(aq) + HSO4

-(aq) H2O(l)



H+(aq) + HSO4

-(aq) H2O(l) molecule

or ion?Which Rule?



H+(aq) + HSO4

-(aq) H2O(l) + SO3(aq)



H+(aq) + HSO4


To check the answer,ask these two questions:



H+(aq) + HSO4


Do both sides of the arrowhave the same number of elements?



H+(aq) + HSO4


Do both sides of the arrowhave the same total charge?

Spectator ionsSpectator ions

Ions appearing onIons appearing on

BOTH sides of BOTH sides of

the equation. the equation.

They are They are assumedassumed

to take no part into take no part in

the reaction and the reaction and

are canceled. are canceled.


They are NOT partThey are NOT part

of a net ionicof a net ionic

equation.equation.


Write in net ionic formWrite in net ionic form

2AgNO3(aq) + H2SO4(aq) Ag2SO4(cr) + 2HNO3(aq)

molecule or ion?


2Ag+(aq) + 2NO3

-(aq)



2Ag+(aq) + 2NO3

-(aq)

molecule or ion?



2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)



2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)molecule

or ion?



2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)

Ag2SO4(cr)



2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)

Ag2SO4(cr)

molecule or ion?



2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)

Ag2SO4(cr) + 2H+(aq) + 2NO3

-(aq)



2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)


-(aq)

Spectator ions?Spectator ions?



2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)


-(aq)




2Ag+(aq) + 2NO3

-(aq) + H+

(aq) + HSO4-(aq)


-(aq)




2Ag+(aq) + HSO4

-(aq) Ag2SO4(cr) + H+

(aq)



2Ag+(aq) + HSO4


(aq)

Are elements balanced?Are elements balanced?



2Ag+(aq) + HSO4


(aq)

Is the charge the sameIs the charge the sameon both sides of the arrow?on both sides of the arrow?



2Ag+(aq) + HSO4


(aq)

This IS theThis IS thenet ionic equation!net ionic equation!


Net Ionic EquationsNet Ionic Equations

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Net Ionic Equations