solution chemistry and solubility 12a—demonstrate and explain effects of temperature and the...
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Solution Chemistry and Solubility
12A—Demonstrate and explain effects of temperature and the nature of solid solutes on the
solubility of solids
13A—Compare unsaturated, saturated, and supersaturated solutions
13B—Interpret relationships among ionic and covalent compounds, electrical conductivity, and
colligative properties of water
Review
Element—substance that cannot be broken down into simpler substances (periodic table)
Compound—a substance made of atoms of more than one element bound together (H2O, CO2, NaCl)
Mixture—a combination of more than one pure substance (Salt water, Powerade, Salad)
Mixture Review
Mixture—a physical blend of two or more substances
Heterogeneous mixture—one that is not uniform in composition
Homogeneous mixture—one that has a completely uniform composition
Mixture Review
Mixture REVIEW You can separate mixtures by PHYSICAL
means Distillation Separation Chromatography
Type Particle size
Settle upon standing
Tyndall effect (Scatter light)
Solutions Homo-geneous
0.01-1 nm No no
Colloid Hetero-geneous
1-1000 nm No Yes
Suspension Hetero-geneous
Greater than 1000 nm
Yes sometimes
Solution Chemistry Solution—a homogeneous mixture Solute—dissolved particles in a solution Solvent—the dissolving medium in a
solution (usually water, the universal solvent)
Kool-Aid Solution
Kool-Aid Juice is the SOLUTION Kool-Aid powder and Sugar are the
SOLUTES Water is the SOLVENT
Soluble vs. Insoluble
Soluble—dissolves completely so that solution looks transparent (free of any floating particles
Insoluble—does not dissolve completely; solution is cloudy
How does dissolving takes place?
What happens when salt is dissolved in water?
NaCl Na+ + Cl-
Complete the dissociation of the following salts:
KCl K+ + Cl-
MgCl2 Mg+2 + 2Cl-
AlCl3 Al+3 + 3Cl-
MgF2Mg+2 + 2F-
Solution Chemistry Electrolytes—compounds that conduct an
electric current ALL ionic compounds; NaCl, CuSO4, NaOH
Nonelectrolytes—Compounds that do not conduct an electric current in either aqueous solution or the molten state Many molecular compounds; carbon, sugar,
alcohol
Electrolytes vs. Nonelectrolytes
Electrolytes vs. Nonelectrolytes Some very polar molecular compounds are
nonelectrolytes in pure state but become electrolytes when dissolved in water
NH3(g) + H2O(l) NH4+(aq) + OH-(aq)
Electrolytes vs. Nonelectrolytes
Weak Electrolyte—only a fraction of the solute exists as ions
Strong Electrolyte—almost all the solute exists as separate ions
Weak Electrolyte in Weak Electrolyte in solution.solution.
Strong electrolyte Strong electrolyte in solution.in solution.
Electrolytes vs. Nonelectrolytes
STRONG ELECTROLYTES Strong acids (HCl, H2SO4, HNO3) Strong bases (NaOH, KOH)
WEAK ELECTROLYTES Weak acids (Vinegar, acetic acid, CH3COOH)
Weak bases (Ammonia, NH3)
NONELECTROLYTES Molecular compounds Nonmetal bonded to nonmetal
Electrolytes vs. Nonelectrolytes
More ions in solutions, the more conductivity Which salt would give more ions: NaCl or
MgCl2?
So, which will conduct electricity more/be a better electrolyte?
Look back at the dissociation reactions and determine the better electrolyte.
Solutions are homogeneous mixtures that could be solid, liquid, or gaseous
Gas Gas Oxygen in nitrogen
Gas Liquid CO2 in water
Liquid Gas Water in air
Liquid Liquid Alcohol in water
Liquid Solid Mercury in silver and tin (dental amalgam)
Solid Liquid Sugar in water
Solid Solid Copper in nickel (alloys)
Solubility Solubility—the amount that dissolves in a
given quantity of a solvent at a given temperature to produce a saturated solution. Solubility is often expressed in grams of solute
per 100g of solvent
Water and Solubility?
REMEMBER water is a POLAR molecule Polar means electrons are not spread evenly
throughout the molecule
Polar molecules dissolve polar molecules Water can dissolve ammonia
Nonpolar molecules dissolve nonpolar molecules Octane (gasoline) can dissolve CO2
LIKE DISSOLVES LIKE!!!!LIKE DISSOLVES LIKE!!!!
Solution Concentration
Concentration—the quantity of solute dissolved in a given quantity of solution Three ways to describe a solution
Unsaturated solutionSaturated solutionSupersaturated solution
Solubility
Unsaturated—a solution that contains less solute than solvent
Saturated—a solution that contains the maximum amount of solute for a given amount of solvent at a constant temperature
Supersaturated—a solution that contains more solute than it can theoretically hold at a given temperature; crystals form
Solubility
Two liquids are said to be MISCIBLE if they dissolve in each other Water and ethanol dissolve in each other
Liquids that are insoluble in each other are IMMISCIBLE. Oil and water do no dissolve in each other
MISCIBLE
Water and alcohol
IMMISCIBLE
Water and oil
Gas Solubility
Henry’s Law—as the pressure of the gas above the liquid increases, solubility of the gas increases and vice versa
Gas Solubility
Henry’s Law
S = solubility P = Pressure
S1 S2
P1 P2
=
Gas Solubility
EXAMPLES Ears Popping Underwater Diving (the bends) Airplane taking off or landing
Factors Affecting Solubility
SURFACE AREA Solutes with larger surface area dissolves faster
Smaller pieces dissolve faster than larger pieces
Factors Affecting Solubility
STIRRING Stirring or shaking a solution helps the solute
dissolve fasterStirring or shaking moves dissolved sugar away from
undissolved sugar crystals
Factors Affecting Solubility
TEMPERATURE Solutes dissolve faster when the solvent is hot
When substance is heated, particles move faster causing more collisions between particles
Factors Affecting Solubility
Things that dissolve in water are called SOLUBLE
Things that do not dissolve in water are called INSOLUBLE
Solubility Curves
Solubility curves (graphs) give the solubility and temperature of a saturated solution.
Solubility is on y-axis Temperature (°C) is on x-axis
Solubility Curve
Solubility Curves
SATURATED solution is ON line or curve UNSATURATED solution is BELOW line
or curve SUPERSATURATED solution is above line
or curve