# Ionic Equations.... Whats really swimming around. And whats Ionic Equations.... Whats really swimming around. And whats not swimming around. 1 Electrolytes: cmpds whose aqueous solutions conduct electricity. (refer to solubility rules). Electrolytic solutions must contain ions. Nonelectrolytes: cmpds whose solutions dont 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. 2 3 Double Replacement Reactions Or to impress your friends. Also called: Metathesis reactions 4 KI(aq) + Pb(NO3)2(aq) KNO3(aq) + PbI2(s)

5 Equation: 2KI(aq) + Pb(NO3)2(aq) 2KNO3(aq) + PbI2(s) Overall Ionic Equation: + - 2K + 2I Beaker A + Pb

2+ + 2NO3 Beaker B - 2K+ + 2NO3- + PbI2(s) Beaker C 6 Equation: 2KI(aq) + Pb(NO3)2(aq) 2KNO3(aq) + PbI2(s)

Overall Ionic Equation: + - 2K + 2I + Pb 2+ + 2NO3 -

2K+ + 2NO3- + PbI2(s) Net Ionic Equation: (Cross out the spectator ions) 2+ Pb + 2I- PbI2(s) These are the ions that form the product 7 All group 1 cmpds are soluble!

8 Lets Take a Quiz!! Which one of the following substances is insoluble in water? a) b) c) d) e) RbOH KSCN BaCO3

LiBr Na3PO4 What do these cmpds look like when they dissolve? 9 What do these cmpds look like when they dissolve? Which one of the following substances is insoluble in water? H2O a) RbOH b) KSCN c) BaCO3 d) LiBr e) Na3PO4

10 Which one of the following is an insoluble base? a) b) c) d) e) RbOH Ba(OH)2 Al(OH)3 LiOH KOH

11 Which one of the following salts is insoluble in water? a) b) c) d) e) FeCl3 Al2(SO4)3 Cr(NO3)3 (NH4)2CO3 AgCl

12 Which one of the following salts is insoluble in water? a) b) c) d) e) MgSO4 KNO3 AgBr FeCl3 NaBr

13 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) Lets find the net ionic equation: (Cross out all the Spectator ions.) Net ionic equation: Ba2+ + SO42- BaSO4(s) 14

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, Hydrobromic, Hydrochloric, Hydroiodic, Nitric, Sulfuric, Perchloric Strong Bases: HClO3

HBr HCl HI Group 1A metal hydroxides (LiOH, NaOH, KOH, RbOH, CsOH) Heavy Group 2A metal hydroxides HNO3 [Ca(OH)2, Sr(OH)2, and H2SO4 Ba(OH)2] HClO4 15

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+ + Cl16 What is a strong Base? A base that is completely dissociated in water (highly soluble). NaOH(s) Na+ + OHStrong 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] 17

RXN: Strong acid and a strong base. HCl(aq) + NaOH(aq) HOH(l) + NaCl(aq) strong H + Cl + Na + OH + nonelectrolyte electrolyte strong - +

- H2O(l) + Na+ + Cl- this is the total or overall ionic equation H+ + OH- H2O(l) Cross out the spectators to find the NET IONIC EQUATION 18 Strong and Weak acids Strong Acids: HClO4 H2SO4

HNO3 HI HBr HCl HClO3 Weak Acids: The Rest Weak electrolytes Strong electrolytes 19

Strong Acids: 100% ionized (completely dissociated) in water. HCl + H2O H3O+ + ClNote the one way arrow. Weak Acids: Only a small % (dissociated) in water. HC2H3O2 + H2O H3O+ + C2H3O2Note the 2-way arrow. Why are they different? 20 Strong Acids: HCl HCl HCl HCl HCl

(H2O) ADD WATER to MOLECULAR ACID 21 Strong Acids: Cl(H2O) H3O+ H3O+ H3O+ H3O+ H3O+

ClCl Cl- - Cl- Note: No HCl molecules remain in solution, all have been ionized in water. 22 Weak Acid Ionization: HC2H3O2

HC2H3O2 HC2H3O2 HC 2H 3O 2 HC2H3O2 (H2O) Add water to MOLECULES of WEAK Acid 23

Weak Acid Ionization: HC2H3O2 HC2H3O2 HC2H3O2 HC 2H 3O 2 HC2H3O2 (H2O)

H30+ C2H3O2- 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. 24 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 25 What is the total ionic equation for the following formula unit equation? HC2H3O2(aq) + NaOH(aq) weak acid

strong base NaC2H3O2(aq) + H2O(l) 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)

26 Net Ionic equations with Single Replacement RXNs: Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s) Over-all: Cu(s) + 2Ag+ + 2NO3- Cu2+ + 2NO3- + 2Ag(s) Cross out the spectator ions. 27

Net Ionic equations with Single Replacement RXNs: Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s) Over-all: Cu(s) + 2Ag+ + 2NO3- Cu2+ + 2NO3- + 2Ag(s) Net ionic Eq.: Cu(s) + 2Ag+ Cu 2+ + 2Ag(s)

Copper is more reactive than silver! 28 29 Lets try: Mg in HCl(aq) Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g) Mg + 2H+ + 2Cl- Mg2+ + 2Cl- + H2(g) 30 Fe in AgNO3(aq)

HCl and NaHCO3(aq) NaOH and H3PO4(aq) 31 Study for a Quiz! 32