Ionic interactions When you dissolve 2 or more ionic compounds in water some parts of it may react together and precipitate out When you dissolve 2 or more ionic compounds in water some parts of it may react together and precipitate out Precipitate-solid falling out of solution Precipitate-solid falling out of solution More times than not, most (if not all) of the ions do nothing More times than not, most (if not all) of the ions do nothing Net ionic equations are only concerned with the ions that do something Net ionic equations are only concerned with the ions that do something

This goes back to ionic dissociation in water NaCl (s) + AgNO 3(s) in water  Na + (aq) + Cl - (aq) + Ag + (aq) + NO 3 - (aq)  Here’s the trick, AgCl is insoluble AgCl (s) + Na + (aq) + NO 3 - (aq) Net ionic ignores everything that doesn’t do anything! Ag + (aq) + Cl - (aq)  AgCl (s) net ionic equation-- 

More net ionic equ. You normally write the reactants as aqueous (since you are dissolving them) You normally write the reactants as aqueous (since you are dissolving them) Mg(NO 3 ) 2(aq) + Na 2 CO 3(aq)  MgCO 3(s) + 2NaNO 3(aq) Mg(NO 3 ) 2(aq) + Na 2 CO 3(aq)  MgCO 3(s) + 2NaNO 3(aq) Dissociate everything that is aqueous, not solid Dissociate everything that is aqueous, not solid Mg NO Na + + CO 3 -- Mg NO Na + + CO 3 -- –  MgCO 3(s) + 2 Na + + 2NO 3 - Now cancel out everything that is the same on both sides of the equation Now cancel out everything that is the same on both sides of the equation These are called spectator ions These are called spectator ions The remaining part is the net ionic equation Mg ++ + CO 3 --  MgCO 3(s)

What if nothing precipitates out? K 2 SO 4(aq) +AgNO 3(aq)  KNO 3(aq) + Ag 2 SO 4(aq) K 2 SO 4(aq) +AgNO 3(aq)  KNO 3(aq) + Ag 2 SO 4(aq) (by the way, this equation isn’t balanced) (by the way, this equation isn’t balanced) 2 K + + SO Ag + + NO 3 -  2 K + + SO Ag + + NO 3 -  –K + + NO Ag + + SO 4 2- Everything cancels out Everything cancels out There is no net ionic equation There is no net ionic equation

Practice with equations that are not yet balanced K 2 CO 3(aq) + Co(NO 3 ) 3( aq) K 2 CO 3(aq) + Co(NO 3 ) 3( aq) –  KNO 3 (aq) + Co 2 (CO 3 ) 3 (s) 2K + + CO Co NO 3 - 2K + + CO Co NO 3 -  Co 3 (CO 3 ) 2(s) + K + + NO 3 -  Co 3 (CO 3 ) 2(s) + K + + NO 3 - Just ignore coefficients when canceling Just ignore coefficients when canceling Co 3+ (aq) + CO 3 2- (aq)  Co 2 (CO 3 ) 3(s) Co 3+ (aq) + CO 3 2- (aq)  Co 2 (CO 3 ) 3(s) Now you balance the equation Now you balance the equation 23

Tip to make sure your answer is right Make sure you have the same atoms on each side of the equation Make sure you have the same atoms on each side of the equation If your final answer is something like If your final answer is something like K + + CO 3 2-  CaCO 3(s) K + + CO 3 2-  CaCO 3(s) It is wrong!!! It is wrong!!! Atoms don’t spontaneously change into other atoms (without a nuclear reaction) Atoms don’t spontaneously change into other atoms (without a nuclear reaction)

Solubility rules Rules to determine if something is soluble (will stay dissolved--aq--) or when it is insoluble (will precipitate out, become a solid--s--) Rules to determine if something is soluble (will stay dissolved--aq--) or when it is insoluble (will precipitate out, become a solid--s--) You will be able to use the solubility rules sheet on the test. You will be able to use the solubility rules sheet on the test.

Soluble Compounds 1. All common compounds of Group I are soluble except LiF, Li 2 S, and Cs 2 S. 2. All ammonium (NH 4 ) compounds are soluble. 3. All acetates (CH 3 COO) are soluble except Fe All nitrates (NO 3 ), and chlorates (ClO 3 ) are soluble.

Soluble Compounds cont. 5. All binary compounds of the halogens (other than F) with metals are soluble, except those of Silver, Mercury(I), and Lead. Pb halides are soluble in hot water. 6. All sulfates are soluble, except those of barium, strontium, calcium, lead, silver, and mercury (I). The latter three are slightly soluble.

Insoluble Compounds 7. Except for rule 1 and 2, carbonates, oxalates, sulfites, chromates, oxides, silicates, and phosphates are insoluble. 8. Except for rule 1 and 2 hydroxides are insoluble except Ba, Sr, and Ca 9. Except for rule 1 and 2, Sulfides are insoluble except for calcium, barium, strontium, magnesium.

Examples K 3 NK 2 CrO 4 K 3 NK 2 CrO 4 Na 2 CO 3 BaSO 3 Na 2 CO 3 BaSO 3 Li 2 S(NH 4 ) 3 PO 4 Li 2 S(NH 4 ) 3 PO 4 NH 4 NO 3 FeSiO 3 NH 4 NO 3 FeSiO 3 Mg(NO 3 ) 2 CuO Mg(NO 3 ) 2 CuO AgClO 3 NaOH AgClO 3 NaOH AgClBaOH AgClBaOH CuF 2 Ni(OH) 2 CuF 2 Ni(OH) 2 CrSO 4 MgS CrSO 4 MgS CaSO 4 BeS CaSO 4 BeS (aq)(aq) (aq)(aq) (aq)(s) (aq)(s) (s)(aq) (s)(aq) (aq)(s) (aq)(s) (aq)(aq) (aq)(aq) (s)(aq) (s)(aq) (s)(s) (s)(s) (aq)(aq) (aq)(aq) (s)(s) (s)(s)

Net Ionic Equations Identify what is soluble or insoluble and write the net ionic equation Identify what is soluble or insoluble and write the net ionic equation CuNO 3 + Na 2 SO 3 → NaNO 3 + Cu 2 SO 3 CuNO 3 + Na 2 SO 3 → NaNO 3 + Cu 2 SO 3 2 Cu + (aq) + SO 3 2- (aq) → Cu 2 SO 3 (s) 2 Cu + (aq) + SO 3 2- (aq) → Cu 2 SO 3 (s) Fe(ClO 3 ) 2 + NaCH 3 COO → NaClO 3 + Fe(CH 3 COO) 2 Fe(ClO 3 ) 2 + NaCH 3 COO → NaClO 3 + Fe(CH 3 COO) 2 No net ionic equation No net ionic equation Pb(NO 3 ) 4 + (NH 4 ) 2 SO 4 → Pb(NO 3 ) 4 + (NH 4 ) 2 SO 4 → Pb(SO 4 ) 2 + NH 4 NO 3 Pb 4+ (aq) + 2 SO 4 2- (aq) → Pb(SO 4 ) 2 (s) Pb 4+ (aq) + 2 SO 4 2- (aq) → Pb(SO 4 ) 2 (s)