Title: Aqueous Reactions and Solution Chemistry
1Aqueous Reactions and Solution Chemistry
2General Properties of Aqueous Solutions
- A solution is a homogeneous mixture of two or
more substances. - Solute The substance being dissolved.
- Solvent The substance present in the greater
amount which is known as the dissolving medium. - Aqueous solution The dissolving medium is water.
3General Properties of Aqueous Solutions
- Electrolytic Properties
- A solution that contains ions conducts
electricity. - Electrolyte A substance whose aqueous solutions
contain ions. (Ionic compounds) - Nonelectrolyte A substance whose aqueous
solutions do not form ions. (Molecular compounds)
- The number and type of ions in solution can be
predicted from the nomenclature of the substance.
4General Properties of Aqueous Solutions
- Ionic compounds dissolve in water through a
process known as solvation which results in ions. - Molecular compounds do not dissociate in water
rather they exist as intact molecules dispersed
through the solution.
5General Properties of Aqueous Solutions
- Strong Electrolyte Those solutes that exist in
solution mainly as ions-equilibrium lies to the
right. - Weak Electrolyte Those solutes that exist in
solution mainly as molecules equilibrium lies to
the left. - The solubility of the electrolyte does not mean
that it is a strong or weak electrolyte (Acetic
acid vs.Ba(OH)2)
6Precipitation Reactions
- The driving forces that allow a chemical reaction
to take place - An insoluble solid is produced.
- A gas is released.
- An acid neutralizes a base.
- One of the ions can oxidize another.
7Precipitation Reactions
- In a exchange or metathesis reaction two ionic
compounds in aqueous solution switch anions and
produce two new compounds. - There is not a reaction if no precipitate is
formed since there is no driving force.
8Precipitation Reactions
- Molecular Equations - reactants and products are
written using their full formulas as if they were
molecules. - Ionic Equations - any reactants or products which
completely dissociate in water are shown in terms
of their free ions. - Net Ionic Equation - the equation for the net
change that takes place during the reaction the
spectator ions are not included.
9Precipitation Reactions
- Write molecular, ionic and net ionic equations
for the reaction betweenPb(NO3)2 and (NH4)2SO4
SnCl2 and NaOH NaNO3 and BaCl2. - Write the molecular, ionic, and net ionic
equations for the reaction between nitric acid
and calcium hydroxide. - Net ionic equations point out the similarities
between large numbers of reactions involving
electrolytes.
10Acid-Base Reactions
- Acids
- Ionize in aqueous solutions to form hydrogen
ions. - Different types of acids
- Monoprotic HCl
- Diprotic H2SO4
- Triprotic H3PO4
- Bases
- Produce OH- ions in water.
11Acid-Base Reactions
- Strong Acids and Bases
- Strong electrolytes since they dissociate
completely in water. - Weak Acids and Bases
- Weak electrolytes since they only partly ionize
in water.
12Oxidation-Reduction Reactions
- Oxidation and Reduction
- Oxidation Losing Electrons
- Reduction Gaining Electrons
- Oxidizing agent Accepts electrons.
- Reducing agent Donates electrons.
- Oxidation-reduction occur at the same time.
13Oxidation-Reduction Reactions
- Oxidation Numbers
- For an atom in its elemental form the oxidation
number is always zero. - For any monoatomic ion the oxidation number
equals the charge on the ion. - Nonmetals usually have negative oxidation numbers
although they can sometimes be positive. - The sum of the oxidation numbers in a compound
equals the charge on the compound.
14Oxidation-Reduction Reactions
- In a single replacement reaction a metal
displaces another metal or hydrogen, from a
compound or aqueous solution that is below it in
the Activity Series.
15Oxidation-Reduction Reactions
- Active metals
- Include most of the metals in Group I, II.
- Ligt Kgt Bagt Srgt Cagt Na
- Active metals react directly with water
- 2Na 2H2O(l) 2NaOH(aq) H2(g)
- Activity Series for Nonmetals
- Fgt Clgt Brgt I
16Oxidation-Reduction Reactions
- Oxidation and reduction can also be described as
- Oxidation Gain of oxygen or loss of hydrogen.
- Reduction Loss of oxygen or the gain of
hydrogen. - Methane is combusted in sufficient oxygen to
produce carbon dioxide and water. Which element,
C or H is reduced, which is oxidized?
17Concentrations of Solutions
- Molarity
- expresses the concentration of a solution as the
number of moles of solute in a liter of solution. - Expressing the Concentration of an Electrolyte
- The relative concentrations of the ions
introduced into the solution depend on the
chemical formula of the compound.
18Concentrations of Solutions
- Dilution
- Process of making a more dilute solution by
adding water to a more concentrated solution. - What volume of 2.50 M lead nitrate solution
contains 0.075 mol of Pb2? - How many mL of 5.0M K2Cr2O7 solution must be
diluted to prepare 250 mL of 0.20 M solution?
19Solution Stoichiometry and Chemical Analysis
- Titrations
- Determines the concentration of a particular
solute in a solution. - Equivalence Point
- Stoichiometrically equivalent quantities of acid
and base are brought together. - Indicators
- show the equivalence point.
20Solution Stoichiometry and Chemical Analysis
- How many mL of 0.120 M HCl are needed to
completely neutralize 50 mL of 0.101 M Ba(OH)2
solution?