# 1 Ionic Equations.... What’s really swimming around. And what’s not swimming around.

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1 Ionic Equations.... What’s really swimming around. And what’s not swimming around.

2 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 H 2 O(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 conduct electricity. No ions are present in solution.

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4 Double Replacement Reactions Also called: Metathesis reactions Or to impress your friends.

5 KI(aq) + Pb(NO 3 ) 2 (aq)  KNO 3 (aq) + PbI 2 (s)

6 2KI(aq) + Pb(NO 3 ) 2 (aq)  2KNO 3 (aq) + PbI 2 (s) 2K + + 2I - Equation: Overall Ionic Equation: + Pb 2+ + 2NO 3 - 2K + + 2NO 3 - + PbI 2 (s) Beaker A Beaker BBeaker C

7 2KI(aq) + Pb(NO 3 ) 2 (aq)  2KNO 3 (aq) + PbI 2 (s) 2K + + 2I - Equation: Overall Ionic Equation: + Pb 2+ + 2NO 3 - 2K + + 2NO 3 - + PbI 2 (s) Net Ionic Equation: (Cross out the spectator ions) Pb 2+ + 2I - PbI 2 (s) These are the ions that form the product

8 All group 1 cmpds are soluble!

9 Which one of the following substances is insoluble in water? a) RbOH b) KSCN c) BaCO 3 d) LiBr e) Na 3 PO 4 Let’s Take a Quiz!! What do these cmpds look like when they dissolve?

10 Which one of the following substances is insoluble in water? a) RbOH b) KSCN c) BaCO 3 d) LiBr e) Na 3 PO 4 What do these cmpds look like when they dissolve? H2OH2O

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

12 Which one of the following salts is insoluble in water? a) FeCl 3 b) Al 2 (SO 4 ) 3 c) Cr(NO 3 ) 3 d) (NH 4 ) 2 CO 3 e) AgCl

13 Which one of the following salts is insoluble in water? a) MgSO 4 b) KNO 3 c) AgBr d) FeCl 3 e) NaBr

14 What is the total ionic equation for the following formula unit equation? BaCl 2 (aq) + Na 2 SO 4 (aq) --> BaSO 4 (s) + 2NaCl(aq) [Ba 2+ (aq)+2Cl - (aq)] + [2Na + (aq)+SO 4 2- (aq)]  BaSO 4 (s) + 2Na + (aq)+2Cl - (aq) Let’s find the net ionic equation: (Cross out all the Spectator ions.) Ba 2+ + SO 4 2-  BaSO 4 (s)Net ionic equation:

15 Common Strong Acids and Bases: Strong Acids: Chloric, HClO 3 Hydrobromic, HBr Hydrochloric, HCl Hydroiodic, HI Nitric, HNO 3 Sulfuric, H 2 SO 4 Perchloric HClO 4 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 ] Strong acids are completely separated into their ions in water. Strong bases are strong electrolyes also. (high solubility)

16 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 + H 2 O  H 3 O + + Cl -

17 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 ]

18 RXN: Strong acid and a strong base. HCl(aq) + NaOH(aq)  HOH(l) + NaCl(aq) strong H + + Cl - + Na + + OH - H 2 O(l) + nonelectrolyteelectrolyte Na + + Cl - “this is the total or overall ionic equation” Cross out the spectators to find the NET IONIC EQUATION H + + OH -  H 2 O(l)

19 Strong and Weak acids Strong Acids: HClO 4 H 2 SO 4 HNO 3 HI HBrHCl HClO 3 Weak Acids: “The Rest” Strong electrolytes Weak electrolytes

20 Strong Acids: 100% ionized (completely dissociated) in water. HCl + H 2 O  H 3 O + + Cl - Note the “one way arrow”. Weak Acids: Only a small % (dissociated) in water. HC 2 H 3 O 2 + H 2 O  H 3 O + + C 2 H 3 O 2 - Note the “2-way” arrow. Why are they different?

21 Strong Acids: HCl ADD WATER to MOLECULAR ACID (H 2 O)

22 Strong Acids: (H 2 O) H3O+H3O+ H3O+H3O+ H3O+H3O+ H3O+H3O+ H3O+H3O+ Cl - Note: No HCl molecules remain in solution, all have been ionized in water.

23 HC 2 H 3 O 2  (H 2 O) Weak Acid Ionization: Add water to MOLECULES of WEAK Acid

24 HC 2 H 3 O 2  H 3 0 + C 2 H 3 O 2 - (H 2 O) 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.

25 What is the total ionic equation for the following formula unit equation? HF(aq) + KOH(aq)  KF(aq) + H 2 O(l) weak strong strong electrolyte non-electrolyte HF(aq) + K + (aq)+OH - (aq)  K + (aq)+F - (aq) + H 2 O(l) Overall ionic equation: Net ionic equation: (Cross out the spectators) HF(aq) + OH - (aq)  F - (aq) + H 2 O(l) HF is a weak acid weak electrolyte

26 What is the total ionic equation for the following formula unit equation? HC 2 H 3 O 2 (aq) + NaOH(aq)  NaC 2 H 3 O 2 (aq) + H 2 O(l) weak acid strong base strong electrolyte weak electrolyte HC 2 H 3 O 2 (aq) + Na + (aq)+OH - (aq)  Na + (aq)+ C 2 H 3 O 2 - (aq) + H 2 O(l) Overall ionic equation: Net ionic equation: (Cross out the spectators) HC 2 H 3 O 2 (aq) + OH - (aq)  C2H3O2 C2H3O2 - (aq) + H 2 O(l)

27 Net Ionic equations with Single Replacement RXNs : Cu(s) + 2AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + 2Ag(s) Cu(s) + 2Ag + + 2NO 3 -  Cu 2+ + 2NO 3 - + 2Ag(s) Over-all: Cross out the spectator ions.

28 Net Ionic equations with Single Replacement RXNs: Cu(s) + 2AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + 2Ag(s) Cu(s) + 2Ag + + 2NO 3 -  Cu 2+ + 2NO 3 - + 2Ag(s) Over-all: Net ionic Eq.: Cu(s) + 2Ag +  Cu 2+ + 2Ag(s) Copper is more reactive than silver!

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30 Let’s try: Mg in HCl(aq) Mg(s) + 2HCl(aq)  MgCl 2 (aq) + H 2 (g) Mg + 2H + + 2Cl -  Mg 2+ + 2Cl - + H 2 (g)

31 Fe in AgNO 3 (aq) HCl and NaHCO 3 (aq)  NaOH and H 3 PO 4 (aq)

32 Study for a Quiz!

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