Chemical Equations & Reactions Chapter 8 Lesson 3

Solubility Rules p Most nitrates are soluble. 2.Most salts containing Group I ion and ammonium ion, NH 4 +, are soluble. 3.Most chloride, bromide, and iodide salts are soluble, except Ag +, Pb 2+ and Hg Most sulfate salts are soluble, except BaSO 4, PbSO 4, Hg 2 SO 4, and CaSO 4. 5.Most hydroxides except Group 1 and Ba(OH) 2, Sr(OH) 2, and Ca(OH) 2 are only slightly soluble. 6.Most sulfides, carbonates, chromates, and phosphates are only slightly soluble.

Ions in Aqueous Solution Pb(NO 3 ) 2 (s) Pb(NO 3 ) 2 (aq) Pb 2+ (aq) + 2 NO 3 1– (aq) add water dissociation: Pb 2+ NO 3 1– Pb 2+ NO 3 1– “splitting into ions” NaI(s) NaI(aq) Na 1+ (aq) + I 1– (aq) Na 1+ I 1– Na 1+ I 1– add water = cations (+) = anions (-)

Check new combinations to decide! (?) For double-replacement rxns(or precipitate rxns), The reaction will occur if any product is: water a gas a precipitate driving forces _ Pb(NO 3 ) 2 (aq) + _ K 2 SO 4 (aq) _ FeCl 3 (aq) + _ Cu(NO 3 ) 2 (aq) Fe 3+ Cl 1– NO 3 1– Pb 2+ NO 3 1– K 1+ SO 4 2- Pb 2+ NO 3 1– K 1+ SO 4 2- (?) Cu 2+ Cl 1– Cu 2+ (?) Fe 3+ NO 3 1– (?) (ppt)(aq) NR _ PbSO 4 (s) + _ KNO 3 (aq) = cations (+) = anions (-)

precipitate: a solid product that forms in an aqueous reaction Na 2 CO 3 (aq) + Ca(NO 3 ) 2 (aq) CaCO 3 (s) + 2NaNO 3 (aq) 2Na 1+ (aq) + CO 3 2– (aq) + Ca 2+ (aq) + 2NO 3 1– (aq) clear Na 2 CO 3 solution clear Ca(NO 3 ) 2 solution cloudy solution containing CaCO 3 (s) and NaNO 3 (aq) = cations (+) = anions (-) CaCO 3 (s) + 2Na 1+ (aq) + 2NO 3 1– (aq) CO 3 2– (aq) + Ca 2+ (aq) CaCO 3 (s) COMPLETE IONIC EQUATION NET IONIC EQUATION SPECTATOR IONS

Mix together ZnSO 4 (aq) and BaCl 2 (aq): ZnSO 4 (aq) BaCl 2 (aq) Zn 2+ (aq) + SO 4 2- (aq)Ba 2+ (aq) + 2 Cl 1– (aq) Ba 2+ Cl 1– Zn 2+ SO 4 2- clear ZnSO 4 solutionclear BaCl 2 solution

Mix them and get the complete ionic equation… __Zn 2+ (aq) + __SO 4 2– (aq) + __Ba 2+ (aq) + __Cl 1– (aq) __BaSO 4 (s) + __Zn 2+ (aq) + __Cl 1- (aq) yields Cancel spectator ions to get net ionic equation… __BaSO 4 (s) Cl 1– __Ba 2+ (aq) + __SO 4 2– aq) 11 Zn 2+ Ba 2+ SO 4 2- Ba 2+ SO 4 2- Ba 2+ SO 4 2- ppt

In a reaction: atoms are rearranged AND mass energy charge are conserved Balancing Chemical Equations = law of conservation of mass same # of atoms of each type on each side of equation

Reaction Conditions and Terminology Certain symbols give important info about a reaction. (s) = solid (l) = liquid (g) = gas (aq) = aqueous (dissolved in H 2 O) NaCl(s) NaCl(aq) More on aqueous… -- “soluble” or “in solution” also indicate that a substance is dissolved in water (usually)

Other symbols… means... Temp. at which we perform rxn. might be given. The catalyst used might be given. means ______ is added to the reaction MgCO 3 (s) MgO(s) + CO 2 (g) C 2 H 4 (g) + H 2 (g)C 2 H 6 (g) Pt C 6 H 5 Cl + NaOHC 6 H 5 OH + NaCl 400 o C “yields” or “produces” heat (i.e., clues about the reaction)

1 How do we know if a reaction will occur? For single-replacement rxns, use Activity Series. Elements above replace elements below. _ Ca + _ FeSO 4 _ Pb + _ Al 2 O 3 _ Fe + _ CaSO 4 No Reaction 111 Li K Ca Na Mg Al Zn Fe Pb H + Cu Hg Ag Au = cations (+) = anions (-)