Unit 4: Chemical Equations and Stoichiometry Net Ionic Equations

Net Ionic Equations For reactions taking place in water many substances dissociate (break apart) into ions To write a net ionic equation you must determine which compounds dissociate and which do not

Net Ionic Rules Which molecules dissociate (break apart)??? Rule 1 – Solids, liquids, and gases Do NOT dissociate Rule 2 – Acids: Strong acids dissociate: HCl, HBr, HI, H2SO4, HNO3, HClO4 Weak acids stay together Rule 3 – Bases: Strong bases dissociate: Group 1 and 2 hydroxides: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2 – except Be(OH)2 Weak bases stay together

Net Ionic Rules Which molecules dissociate (break apart)??? Rule 4 – Ionic Compounds: If soluble: dissociate If insoluble: stay together **Use the table on p. 125 in your textbook or the chart on your periodic table

Net Ionic Practice H2SO4 FeS KOH Ca(NO3)2 Cu3(PO4)2 Determine whether the following compounds dissociate in water or not: H2SO4 FeS KOH Ca(NO3)2 Cu3(PO4)2

Net Ionic Equations For reactions taking place in water many substances dissociate (break apart) into ions To write a net ionic equation you must determine which compounds dissociate and which do not Spectator ions: ions that do not actually participate in the reaction

Steps to Writing Net Ionic Equations Example: Hydrochloric acid solution and sodium hydroxide solution yield water and dissolved sodium chloride Step 1 – Write and balance the molecular form: HCl (aq) + NaOH (aq)  H2O (l) + NaCl (aq) Step 2 – Determine which molecules dissociate and rewrite in ionic form: H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq)  H2O(l) + Cl-(aq) + Na+(aq) Spectator ions Step 3 – Cancel ions that appear on both sides and rewrite what is left: H+ (aq) + OH- (aq)  H2O (l)

Net Ionic Example #1 Nickel nitrate + sodium hydroxide  nickel hydroxide + sodium nitrate

Net Ionic Example #2 on the WS Nickel nitrate + sodium hydroxide  nickel hydroxide + sodium nitrate

Net Ionic Decision Making Tree