General Chemistry (CHM 1045) Chapter 4: Reactions in Aqueous Solutions - H2 O is the “universal solvent” - Green solvent o Cheapo Everywhereo Nontoxic - Solution -homogeneous mixture of 2 or more substances o Solute - substance present in smaller amountso Solvent - substance present in larger amounts - Aqueous solution- water is the solvent o Solutes will be: Electrolyte - substance that when dissolved in water conducts electricity Nonelectrolyte - substance that does not conduct electricity when dissolved in water o Ionic compounds are strong electrolytes because they dissolve/dissociate in (+) and (-) ions in H2O Ex: NaCl( s)H2O Na+( aq)+Cl−( aq) o Arrow indicates complete dissociation - Strong acids are also good electrolytes Ex: HCl( g)H2O H+(aq )+Cl−(aq )- Weak electrolytes do not completely dissociate Ex: Acetic acid CH3COOH(aq )H2O CH3COO−( aq)+H+( aq) - Double arrow signifies reversible reaction: “equilibrium arrows”Types of Reactions (RXNs) 1. Precipitation reactions2. Acid-base reactions3. Oxidation-reduction reaction (redox) - Precipitation reaction → a precipitate (insoluble product) is formed o Ex: Pb( NO3)2( aq)+2 KI(aq )→ PbI2( s )+2 KNO3 ( s)- Notice that Pb2+ and K+ ions exchanged anions: “double displacement reaction” or “metathesis reaction” - Whether or not a precipitate (ppt) will form is based on its solubility o Solubility - Max amount of solute that will dissolve in a given quantity of solvent at a certain temperature - Ions that are not involved in precipitate formation are called spectator ions o Ex: Pb(aq )2++3 NO3( aq )−+2 K( aq )++2 I(aq)−→PbI2 ( s)+2 K(s)++2 NO3(s )−o Since they are on both sides of the equation, they can be eliminated to give our net ionic equationPb(aq )2++2 I(aq )−→
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