REACTIONS IN AQUEOUS SOLUTIONS CHAPTER 8-3

Net Ionic Equations Complete ionic equation Many important reactions take place in water - that is, in aqueous solutions. Most ionic compounds dissociate, or separate, into cations and anions when they dissolved in water. In a double replacement reaction like: AgNO3(aq) + NaCl(aq)  AgCl(s) + NaNO3(aq) can be written in a complete ionic equation. Ag+(aq) + NO3- (aq) + Na+(aq) + Cl-(aq)  AgCl(s) + Na+(aq) + NO3- (aq)

The net ionic equation is Spectator ions Net ionic equation The equation is then simplified by eliminating ions that do not participate in the reaction, canceling ions that appear on both sides of the equation. Ions that appear on both sides of the equation are called Spectator ions. Ag+(aq) + NO3- (aq) + Na+ (aq) + Cl-(aq)  AgCl(s) + Na+ (aq) + NO3- (aq) Spectator ions = Na+ and NO3- . The net ionic equation is Ag+(aq) + Cl-(aq)  AgCl(s)

Steps to Write Net Ionic Equations 1st Step 2nd Step Write the normal chemical equations and balance. Na2SO4 + Ba(NO3)2  BaSO4 + 2 NaNO3 Identify the states of matter of each compound in the equation. Na2SO4(aq) + Ba(NO3)2 (aq)  BaSO4 (s) + 2 NaNO3 (aq)

Complete ionic equation 3rd Step Complete ionic equation 4th Step 5th Step Net ionic equation Determine which compounds will dissociate into cations and anions. Write the complete ionic equation and make sure it is balanced. 2Na+(aq)+ SO4-2(aq)+ Ba+2 + 2NO3-(aq)  BaSO4 (s)+2Na+(aq)+ 2NO3-(aq) Eliminate spectator ions 2Na+(aq)+ SO4-2(aq)+ Ba+2 (aq) + 2NO3-(aq)  BaSO4 (s)+ 2Na+(aq)+ 2NO3-(aq) Write net ionic equation SO4-2(aq) + Ba+2(aq)  BaSO4 (s)