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Ionic Equations. What’s really swimming around. And what’s not swimming around. Electrolytes: cmpds whose aqueous solutions conduct electricity. (refer to solubility rules). Electrolytic solutions must contain ions. Nonelectrolytes: cmpds whose solutions don’t conduct
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Ionic Equations.... What’s really swimming around. And what’s not swimming around.
Electrolytes: cmpds whose aqueous solutions conduct electricity. (refer to solubility rules). Electrolytic solutions must contain ions. Nonelectrolytes: cmpds whose solutions don’t conduct electricity. No ions are present in solution. 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.
Double Replacement Reactions Or to impress your friends. Also called: Metathesis reactions
Equation: 2KI(aq) + Pb(NO3)2(aq)2KNO3(aq) + PbI2(s) Overall Ionic Equation: Beaker B 2K++ 2NO3- Beaker C Beaker A 2K+ + 2I- + Pb2+ + 2NO3- + PbI2(s)
Equation: 2KI(aq) + Pb(NO3)2(aq)2KNO3(aq) + PbI2(s) Overall Ionic Equation: 2K++ 2NO3- 2K+ + 2I- + Pb2+ + 2NO3- + PbI2(s) Net Ionic Equation: (Cross out the spectator ions) + 2I- Pb2+ PbI2(s) These are the ions that form the product
Let’s Take a Quiz!! Which one of the following substances is insoluble in water? a) RbOH b) KSCN c) BaCO3 d) LiBr e) Na3PO4 What do these cmpds look like when they dissolve?
What do these cmpds look like when they dissolve? Which one of the following substances is insoluble in water? a) RbOH b) KSCN c) BaCO3 d) LiBr e) Na3PO4 H2O
Which one of the following is an insoluble base? a) RbOH b) Ba(OH)2 c) Al(OH)3 d) LiOH e) KOH
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
Which one of the following salts is insoluble in water? a) MgSO4 b) KNO3 c) AgBr d) FeCl3 e) NaBr
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.) Net ionic equation: Ba2+ + SO42- BaSO4(s)
Common Strong Acids and Bases: Strong acids are completely separated into their ions in water. Strong bases are strong electrolyes also. (high solubility) Strong Acids: Chloric, HClO3 Hydrobromic, HBr Hydrochloric, HCl Hydroiodic, HI Nitric, 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, and Ba(OH)2]
What is a strong Acid? An Acid that is 100% ionized in water. Strong Acids: 100% ionized (completely dissociated) in water. HCl + H2O H3O+ + Cl- often written as: HCl H+ + Cl-
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, and Ba(OH)2]
RXN: Strong acid and a strong base. HCl(aq) + NaOH(aq) HOH(l) + NaCl(aq) nonelectrolyte electrolyte strong strong Na+ + Cl- H2O(l) + Na+ + OH- H+ + Cl- + “this is the total or overall ionic equation” H+ + OH- H2O(l) Cross out the spectators to find the NET IONIC EQUATION
Strong and Weak acids Strong Acids: HClO4 H2SO4 HNO3 HI HBr HCl HClO3 Weak Acids: “The Rest” Weak electrolytes Strong electrolytes
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?
Strong Acids: HCl HCl HCl HCl HCl (H2O) ADD WATER to MOLECULAR ACID
Strong Acids: Cl- H3O+ (H2O) Cl- H3O+ H3O+ Cl- Cl- H3O+ H3O+ Cl- Note: No HCl molecules remain in solution, all have been ionized in water.
Weak Acid Ionization: HC2H3O2 HC2H3O2 (H2O) HC2H3O2 HC2H3O2 HC2H3O2 Add water to MOLECULES of WEAK Acid
Weak Acid Ionization: HC2H3O2 HC2H3O2 (H2O) HC2H3O2 H30+ C2H3O2- HC2H3O2 HC2H3O2 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.
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 Overall ionic equation: HF(aq) + K+(aq)+OH-(aq) K+(aq)+F-(aq) + H2O(l) Net ionic equation: (Cross out the spectators) HF(aq) + OH-(aq) F-(aq) + H2O(l) HF is a weak acid weak electrolyte
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 Overall ionic equation: HC2H3O2(aq) + Na+(aq)+OH-(aq) Na+(aq)+ C2H3O2-(aq) + H2O(l) Net ionic equation: (Cross out the spectators) HC2H3O2(aq) + OH-(aq) C2H3O2-(aq) + H2O(l)
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.
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: Cu(s) + 2Ag+ Cu2++ 2Ag(s) Net ionic Eq.: Copper is more reactive than silver!
Let’s try: Mg in HCl(aq) Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g) Mg + 2H+ + 2Cl- Mg2+ + 2Cl- + H2(g)
Fe in AgNO3(aq) HCl and NaHCO3(aq) NaOH and H3PO4(aq)