reactions in aqueous solutions section 10.3. objectives describe aqueous solutions write complete...
TRANSCRIPT
Reactions in Aqueous Reactions in Aqueous SolutionsSolutions
Section 10.3
Objectives
Describe aqueous solutions Write complete ionic and net ionic
equations for chemical reactions in aqueous solutions
Predict whether reactions in aqueous solutions will produce a precipitate, water, or gas.
Key Terms
Solute Solvent Aqueous solution
Complete ionic equation Spectator ion Net ionic equation
Review of Solutions
Solvent- More plentiful substance in solution
Solute- The compound dissolved in the solvent
Aqueous solution- Solution in which the solvent is water
Aqueous Solutions Many possible solutes:
– Molecular compounds that exist as molecules
• Sucrose
• Ethanol– Molecular compounds that exist as ions
• HClHCl(g) H + (aq) = Cl- (aq)
Aqueous Solutions (cont)
– Ionic compounds that exist as ions
• NaOHNaOH(aq) Na + (aq) + OH- (aq)
Aqueous Solutions When two aqueous solutions containing ions
react it is always a double replacement reaction. The water does not react There are three possible products when aqueous
solutions react:– Precipitates– Water– Gases
Reactions that form Precipitates
Double-replacement reaction
2NaOH(aq) + CuCl2 (aq) 2NaCl (aq) + Cu(OH)2(s)
Ionic equations are used to show the details of reactions involving ions
Writing Ionic Equations You must show the reactants and the product as
ions A complete ionic equation shows all of the
particles in the solution as they realistically exist. A net ionic equation only shows particles that
participate in the reaction. To write a net ionic equation from a complete
ionic equation eliminate all spectators.
Complete Ionic Equations
AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq)
What type of reaction is this? Ag+(aq) + NO3
-(aq) + Na+ (aq) + Cl-(aq) AgCl(s) + Na+ (aq) + NO3
-(aq)
Spectator Ions
Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) AgCl(s) + Na+(aq) + NO3-(aq)
Ions that are not directly involved in a reaction are called spectator ions– They appear on both sides of the arrow exactly
the same way
Net Ionic Equation
Eliminate spectators and rewrite the equation
Ag+(aq) + Cl-(aq) AgCl(s)
Ionic Equations
Make sure that the net charge is balanced. For example…
Pb(s) + 2Cl-(aq) PbCl2(s)
Reactions that Form Water
Double-replacement reactions Water molecules increase the number of
solvent particles No evidence of reaction is observable
(water is colorless and odorless)
HBr(aq) + NaOH(aq) H2O (l) + NaBr(aq)
Practice Write the complete ionic and net ionic
equations for the example:
HBr(aq) + NaOH(aq) H2O (l) + NaBr(aq)
Reactions that Form Gases
Double-replacement reactions Gas-producing Common gases:
– Carbon dioxide– Hydrogen cyanide– Hydrogen sulfide
Practice Write the complete and net ionic equations
for this gas-producing reaction:
2HI(aq) + Li2S(aq) H2S(g) + 2LiI(aq)
Homework
47-51 on page 299