SOLUTIONS
D’ CHEMISTRY OF
SOME DEFINITIONSA solution is a
_______________ mixture of 2 or more substances in a single phase.
One constituent is usually regarded as the SOLVENT and the others as SOLUTES.
SOME DEFINITIONSSolutions are
homogeneous mixtures of two or more pure substances.
In a solution, the solute is dispersed uniformly throughout the solvent.
PARTS OF A SOLUTION
• SOLUTE – the part of a solution that is being dissolved
(usually the lesser amount)• SOLVENT – the part of
a solution that dissolves the solute
(usually the greater amount)• Solute + Solvent =
Solution
ACTIVITY 2.1 IDENTIFYING COMPONENTS OF SOLUTIONS
Solution Solute Solvent
Air in balloon
Ammonia water
Rubbing alcohol (70%)
Rubbing alcohol (40%)
Tincture of Iodine
Sea water
O2 N2
NH3 H2O
H2O Isopropyl alcohol
H2OEthyl alcohol
Iodine Alcohol
Salt H2O
WHICH IS WHICH 1st ROUNDIdentify the solute and solvent in each of the
following solutions.
1.0 g of sugar dissolved in 100 g of water. 50 mL of water mixed with 20 mL isopropyl alcohol A tincture of Iodine is prepared with 0.10 g I2 and 10.0 mL of
ethyl alcohol. 40 % ethanol a rubbing alcohol.
Sugar is the smaller quantity that is dissolving. Therefore it the solute and water is the solvent. Since both water and isopropyl alcohol are liquids, the one smaller volume, is the solute and
water is the solvent. Iodine is the solute and ethyl alcohol is the solvent. Ethanol is the solvent and water is the solute.
WHICH IS WHICH 2nd ROUNDIdentify the solute and solvent in each of the
following solutions.
10 g NaCl and 100 g of water. 50 mL ethanol and 10 mL H2O 2.0 L oxygen and 8.0 L nitrogen.100 g silver and 40 g mercury. 100 mL H2O and 5.0 g sugar
TYPE OF SOLUTION Gas Liquid Solid
SOLUTION SOLUTE SOLVENT EXAMPLE
Gas in a gas
Gas in a liquid
Liquid in a liquid
Solid in a liquid
Liquid in a solid
Solid in a solid
SOME EXAMPLES OF SOLUTION
AirOxygen Nitrogen
Soda waterCO2 H2O
VinegarAcetic acid H2O
Sugar syrupSugar H2O
Dental amalgamAgHg
Brass or SteelZinc CopperCarbon Iron
WATERD’ UNIVERSAL SOLVENT
H2O
FORMED?
HOW SOLUTIONS ARE
DEFINE SOLUTIONSSolutions are
homogeneous mixtures of two or more pure substances.
In a solution, the solute is dispersed uniformly throughout the solvent.
1. Solvent molecules attracted to surface ions.2. Each ion is surrounded by solvent molecules.3. Enthalpy (DH) changes with each interaction broken or formed.
How Does a Solution Form?
Ionic solid dissolving in water
The ions are solvated
(surrounded by solvent).If the solvent is
water, the ions are hydrated.
The intermolecular forces.
How Does a Solution Form?
solvation is an interaction of a solute with the solvent, which leads to stabilization of the solute in the solution.
What is solvation?
Dilute small amount of solute dispersed in the solvent
Concentrated large amount of solute is dissolved in the solvent
KINDS OF SOLUTION
Types of Solutions Based on Solute Concentration…
Hypotonic(lower solute concentration) to the solution
Hypertonic(higher solute concentration) to the solution
Isotonic solutions are equal in their solute concentrations. We say that theyare isotonic to each other.
Types of Solutions Based on Solute Concentration…
How does a solid dissolve into a liquid?
What ‘drives’ the dissolution process?
What are the energetics of dissolution?
QUESTIONS THAT NEEDS SOLUTIONS…
• is the process by which a solid, liquid or gas forms a solution in a solvent.
WHAT IS DISSOLUTION ?
• In solids this can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent.
DISSOLUTION PROCESS IN SOLIDS…
• For liquids and gases, the molecules must be compatible with those of the solvent for a solution to form.
DISSOLUTION PROCESS IN LIQUIDS & GASES…
Dissolution vs Reaction
• Dissolution is a physical change—you can get back the original solute by evaporating the solvent.
• If you can’t, the substance didn’t dissolve, it reacted.
Ni(s) + HCl (aq) NiCl2(aq) + H2(g) NiCl2(s)dry
SOLUBILITY?DEFINE
What is Solubility?
• refers to the maximum amount of solute, expressed
in grams, that can be dissolved in 100 g of water at a specific temperature &
pressure.
Soluble a substance that dissolves in a solvent
Insoluble a substance that does not dissolve in a solvent (sand is insoluble in water)
VOCABULARY
LABORATORY ACTIVITY 2.7SOLUBILITY IN WATER
SUBSTANCES KEROSENE OILETHYL
ALCOHOL WATER
SugarSalt DetergentPowdered chalk Powdered charcoalSulfur powderCuSO4
KMnO4
INSOLUBLEINSOLUBLEINSOLUBLE
INSOLUBLE
SOLUBLE
SOLUBLE
INSOLUBLEINSOLUBLE
INSOLUBLEINSOLUBLEINSOLUBLE
INSOLUBLE
SOLUBLE
SOLUBLE
INSOLUBLEINSOLUBLE
SOLUBLESOLUBLESOLUBLE
SOLUBLE
INSOLUBLE
INSOLUBLE
SOLUBLESOLUBLE
S/SOLUBLES/SOLUBLES/SOLUBLE
S/SOLUBLE
S/SOLUBLE
S/SOLUBLE
S/SOLUBLES/SOLUBLE
Immiscible Two liquids that are insoluble (Oil & Vinegar)
Miscible Two liquids that are soluble in each other (Alcohol & Water)
VOCABULARY
SOLVENT WATER KEROSENE ACETONE ALCOHOL
Oil IMMISCIBLE MISCIBLE MISCIBLE S/MISCIBLE
Saturated solutionSolvent holds as much
solute as is possible at that temperature.
Undissolved solid remains in flask.
Dissolved solute is in dynamic equilibrium with solid solute particles.
Degree of Saturation
Unsaturated SolutionLess than the
maximum amount of solute for that temperature is dissolved in the solvent.
No solid remains in flask.
Degree of Saturation
Supersaturated Solvent holds more solute than is normally possible at that
temperature.These solutions are unstable; crystallization can often be
stimulated by adding a “seed crystal” or scratching the side of the flask.
Degree of Saturation
SOLUBILITYFACTORS AFFECTING
Factors Affecting Solubility
• Chemists use the axiom
• “like dissolves like”Polar substances
tend to dissolve in polar solvents.
Nonpolar substances tend to dissolve in nonpolar solvents.
LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
SOLVENT NaCl C12H22O11 C10H8 I2
Water
SOLVENT WATER KEROSENE ACETONE ALCOHOL
Oil IMMISCIBLE MISCIBLE MISCIBLE S/MISCIBLE
SOLUBLE SOLUBLE INSOLUBLE INSOLUBLE
TemperatureGenerally, the solubility of solid solutes in liquid solvents increases with increasing temperature.
LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
SOLUTE COLD WATER
HOT WATER
TIME TO DISSOLVE
Salt
Sugar
KNO3
TAKES TIME TO DISSOLVE
EASILYDISSOLVED
TAKES TIME TO DISSOLVE
TAKES TIME TO DISSOLVE
EASILYDISSOLVED
EASILYDISSOLVED
TemperatureThe opposite is true
of gases. • Higher temperature
drives gases out of solution.Carbonated soft drinks
are more “bubbly” if stored in the refrigerator.
Warm lakes have less O2 dissolved in them than cool lakes.
Molecular Size The larger the molecules of the solute are, the larger is their molecular
weight and their size. It is more difficult it is for solvent molecules to surround bigger
molecules. If all of the above mentioned factors all excluded, a general rule can be
found that larger particles are generally less soluble. If the pressure, and temperature are the same than out of two solutes of
the same polarity, the one with smaller particles is usually more soluble.
LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
SOLVENT REFINED SALT ROCK SALT
Water
SOLVENT REFINED KNO3 KNO3 CRYSTALS
Water
TAKES TIME TO DISSOLVE
EASILYDISSOLVED
TAKES TIME TO DISSOLVE
EASILYDISSOLVED
Effect of Stirring
Stirring only increases the speed of the process - it increases the movement of the solvent that exposes solute , thus enabling solubility.
As molecules in liquid substances are in constant move, the process would take place anyway, but it would take more time.
LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
SOLUTE SET-UP W/ STIRRING
UNDISTURBED SET-UP
TIME TO DISSOLVE
CuSO4
KNO3
DISSOLVESFASTER
DISSOLVESFASTER
TAKES TIMEDISSOLVES
TAKES TIMEDISSOLVES
Factors Affecting Solubility
The stronger the intermolecular attractions between solute and solvent, the more likely the solute will dissolve.
Example: ethanol in waterEthanol = CH3CH2OH
Intermolecular forces = H-bonds; dipole-dipole; dispersion
Ions in water also have ion-dipole forces.
Factors Affecting Solubility
Glucose (which has hydrogen bonding)
is very soluble in water.
Cyclohexane (which only has dispersion forces)
is not water-soluble.
Factors Affecting Solubility
• Vitamin A is soluble in nonpolar compounds (like fats).
• Vitamin C is soluble in water.
Which vitamin is water soluble and which is fat soluble?
HEALTH APPLICATION
Gases in Solution
• In general, the solubility of gases in water increases with increasing mass.
Why?• Larger molecules
have stronger dispersion forces.
Gases in Solution• The solubility of
liquids and solids does not change appreciably with pressure.
• But, the solubility of a gas in a liquid is directly proportional to its pressure.
Increasing pressure
above solution forces
more gas to
dissolve.
Henry’s LawStates that:
Henry’s LawSg = kPg
Where:
• Sg is the solubility of the gas;
• k is the Henry’s law constant for that gas in that solvent;
• Pg is the partial pressure of the gas above the liquid.