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Ionic Equations....What’s really swimming around.

And what’s not swimming around.

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For a RXN to occur, at least one product must a non-electrolyte. An insoluble solid (s) or a molecular substance such as a gas (g), or liquid (l) [as in H2O(l)]

If everything remains aqueous (aq), no reaction occurs. All particles are ions and are spectators.

Electrolytes: cmpds whose aqueous solutions conduct electricity. (refer to solubility rules). Electrolytic solutions must contain ions.

Nonelectrolytes: cmpds whose solutions don’t conductelectricity. No ions are present in solution.

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Double Replacement Reactions

Also called:Metathesis reactions

Or to impress your friends.

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KI(aq) + Pb(NO3)2(aq) KNO3(aq) + PbI2(s)

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2KI(aq) + Pb(NO3)2(aq) 2KNO3(aq) + PbI2(s)

2K+ + 2I-

Equation:

Overall Ionic Equation:

+ Pb2+ + 2NO3- 2K+ + 2NO3

- + PbI2(s)

Beaker A Beaker B Beaker C

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2KI(aq) + Pb(NO3)2(aq) 2KNO3(aq) + PbI2(s)

2K+ + 2I-

Equation:

Overall Ionic Equation:

+ Pb2+ + 2NO3- 2K+ + 2NO3

- + PbI2(s)

Net Ionic Equation: (Cross out the spectator ions)

Pb2+ + 2I- PbI2(s)

These are the ions that form the product

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All group 1 cmpds are soluble!

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Which one of the following substances is insoluble in water?

a) RbOH b) KSCNc) BaCO3

d) LiBre) Na3PO4

Let’s Take a Quiz!!

What do these cmpds look like when they dissolve?

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Which one of the following substances is insoluble in water?

a) RbOH b) KSCNc) BaCO3

d) LiBre) Na3PO4

What do these cmpds look like when they dissolve?

H2O

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Which one of the following is an insoluble base?

a) RbOHb) Ba(OH)2 c) Al(OH)3

d) LiOHe) KOH

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Which one of the following salts is insoluble in water?

a) FeCl3

b) Al2(SO4)3

c) Cr(NO3)3

d) (NH4)2CO3

e) AgCl

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Which one of the following salts is insoluble in water?

a) MgSO4

b) KNO3

c) AgBrd) FeCl3

e) NaBr

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What is the total ionic equation for the following formula unit equation?

BaCl2(aq) + Na2SO4(aq) --> BaSO4(s) + 2NaCl(aq)

[Ba2+(aq)+2Cl-(aq)] + [2Na+(aq)+SO42-(aq)]

BaSO4(s) + 2Na+(aq)+2Cl-(aq)

Let’s find the net ionic equation:(Cross out all the Spectator ions.)

Ba2+ + SO42- BaSO4(s) Net ionic equation:

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Common Strong Acids and Bases:

Strong Acids:

Chloric, HClO3

Hydrobromic, HBrHydrochloric, HClHydroiodic, HINitric, HNO3

Sulfuric, H2SO4

Perchloric HClO4

Strong Bases:

Group 1A metal hydroxides(LiOH, NaOH, KOH,RbOH, CsOH)

Heavy Group 2A metal hydroxides[Ca(OH)2, Sr(OH)2, andBa(OH)2]

Strong acids are completely separated into their ions in water.

Strong bases are strong electrolyes also. (high solubility)

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What is a strong Acid?

An Acid that is 100% ionized in water.

often written as:

HCl H+ + Cl-

Strong Acids:100% ionized (completely dissociated) in water.

HCl + H2O H3O+ + Cl-

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What is a strong Base?

A base that is completely dissociated in water (highly soluble).

NaOH(s) Na+ + OH-

Strong Bases:

Group 1A metal hydroxides(LiOH, NaOH, KOH,RbOH, CsOH)

Heavy Group 2A metal hydroxides[Ca(OH)2, Sr(OH)2, andBa(OH)2]

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RXN: Strong acid and a strong base.

HCl(aq) + NaOH(aq) HOH(l) + NaCl(aq)strong

H+ + Cl- +strong

Na+ + OH- H2O(l) + nonelectrolyte electrolyte

Na+ + Cl-

“this is the total or overall ionic equation”

Cross out the spectators to find theNET IONIC EQUATION

H+ + OH- H2O(l)

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Strong and Weak acids

Strong Acids:HClO4 H2SO4

HNO3 HIHBr HClHClO3

Weak Acids:“The Rest”

Strong electrolytes

Weak electrolytes

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Strong Acids:100% ionized (completely dissociated) in water.

HCl + H2O H3O+ + Cl- Note the “one way arrow”.

Weak Acids:Only a small % (dissociated) in water.

HC2H3O2 + H2O H3O+ + C2H3O2-

Note the “2-way” arrow.

Why are they different?

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Strong Acids:

HCl HCl HClHCl HCl

ADD WATER to MOLECULAR ACID

(H2O)

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Strong Acids:

(H2O)H3O+

H3O+

H3O+

H3O+

H3O+

Cl-

Cl-

Cl-

Cl-

Cl-

Note: No HCl molecules remain in solution, all have been ionized in water.

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HC2H3O2

HC2H3O2

HC2H3O2

HC

2H3O

2

HC2H3O2

(H2O)

Weak Acid Ionization:

Add water to MOLECULES of WEAK Acid

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HC2H3O2

HC2H3O2

HC2H3O2

HC

2H3O

2

HC2H3O2

H30

+ C2H3O2-

(H2O)

Weak Acid Ionization:

Note: At any given time only a small portion of the acid molecules are ionized and since reactions are running in BOTH directions the mixture composition stays the same.

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What is the total ionic equation for the following formula unit equation? HF(aq) + KOH(aq) KF(aq) + H2O(l) weak strong strong electrolyte non-electrolyte

HF(aq) + K+(aq)+OH-(aq) K+(aq)+F-(aq) + H2O(l)

Overall ionic equation:

Net ionic equation: (Cross out the spectators)

HF(aq) + OH-(aq) F-(aq) + H2O(l)

HF is a weak acidweak electrolyte

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What is the total ionic equation for the following formula unit equation? HC2H3O2(aq) + NaOH(aq) NaC2H3O2(aq) + H2O(l) weak acid strong base strong electrolyte weak electrolyte

HC2H3O2(aq) + Na+(aq)+OH-(aq) Na+(aq)+ C2H3O2 -(aq) + H2O(l)

Overall ionic equation:

Net ionic equation: (Cross out the spectators)

HC2H3O2(aq) + OH-(aq) C2H3O2 -(aq) + H2O(l)

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Net Ionic equations with Single Replacement RXNs:

Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

Cu(s) + 2Ag+ + 2NO3- Cu2+ + 2NO3

- + 2Ag(s)Over-all:

Cross out the spectator ions.

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Net Ionic equations with Single Replacement RXNs:

Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

Cu(s) + 2Ag+ + 2NO3- Cu2+ + 2NO3

- + 2Ag(s)Over-all:

Net ionic Eq.:

Cu(s) + 2Ag+ Cu2+ + 2Ag(s)

Copper is more reactive than silver!

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Let’s try: Mg in HCl(aq)

Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g) Mg + 2H+ + 2Cl- Mg2+ + 2Cl- + H2(g)

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Fe in AgNO3(aq)

HCl and NaHCO3(aq)

NaOH and H3PO4(aq)

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Study for a Quiz!