Introduction Many reactions involve substances dissolved in water. When this happens, solutions form –Solutions (homogeneous substances) Two parts: –SOLUTES- substances dissolved in water –SOLVENTS- the most plentiful substance in a solution
Water, the universal solvent (H 2 O) Examples of Solutes: –Molecular compounds that exist as molecules –Molecular compounds that form ions when they dissolve in water (H+ ions=acids) –Ionic compounds When dissolved in water, the ions can separate
The Products When 2 aqueous solutions that contain ions are combined, the ions may react with one another in a DOUBLE- REPLACEMENT reaction producing: A.Precipitate (s) A. Precipitate (s) B. Water (l) C. Gas (g)
A. Precipitate Use ionic equations to show the details of reactions that involve ions in aqueous solutions Substances are written as ions Complete ionic equations- show all particles involved in a chemical reaction
AgCl (s) NaCl (aq) + AgNO 3 (aq) NaNO 3 (aq) + AgCl (s) Complete: Na + (aq) + Cl - (aq) + Ag + (aq) + NO 3 - (aq) Na + (aq) + NO 3 - (aq) + AgCl (s)
Spectator Ions Notice, that there are ions that appear on both sides of the equation These ions do not participate in the formation of the solid product These ions are called spectator ions. –What were the spectator ions in the previous slide?
Net Ionic Equations Equations that show only the ions involved- omitting the spectator ions are called complete ionic equations! From the previous example: Cl - + Ag + AgCl (s)
Practice! Write the chemical, balanced, complete ionic and net ionic equation for the following: Aqueous solutions of potassium iodide and silver nitrate are mixed, forming the precipitate silver iodide. See white board for solution!
B. Water Some reactions form water No evidence of the chemical reaction can be observed. Why? Example: HCl (aq) + KOH (aq) H 2 O (l) + KCl (aq) H + (aq) + OH - (aq) H 2 O (l)
Practice! Sulfuric acid (H 2 SO 4 ) and aqueous potassium hydroxide react to produce water and potassium sulfate.
C. Gas Common gases produced: carbon dioxide, hydrogen cyanide, and hydrogen sulfide Example: H 2 S (g) Na 2 S (aq) + HCl (aq) NaCl (aq) + H 2 S (g)
Practice! Sulfuric acid and aqueous rubidium sulfide with production of hydrogen sulfide gas