SOLUTIONS
1. A SOLUTION
IS A HOMOGENEOUS MIXTURE OF TWO OR MORE SUBSTANCES IN A
2. IN A SOLUTION ONE SUBSTANCE IS DISSOLVED IN ANOTHER
A. THE SUBSTANCE DISSOLVED IS CALLED THE SOLUTE
B. THE SUBSTANCE DOING THE DISSOLVING IS CALLED THE SOLVENT. (EXAMPLE: WATER IS A GOOD CLEANING SOLVENT.)
3. TYPES OF SOLUTIONS
A. SOLID SOLUTIONS ALLOYS (TWO OR MORE METALS MIXED TOGETHER)
B. GAS SOLUTIONS EX. OUR ATMOSPHERE
C. LIQUID SOLUTIONS MOST COMMONLY THOUGHT OF AS A SOLUTION
1. LIQUID IN LIQUID ALCOHOL IN WATER
2. GAS IN LIQUID CO2 IN POP
3. SOLID IN LIQUID SALT WATER
4. AQUEOUS SOLUTIONS HAVE WATER AS A SOLVENT.
A. THERE ARE TWO KINDS
1. THOSE THAT FORM IONS AND CONDUCT ELECTRICTY. THEY ARE CALLED ELECTROLYTES
2. THOSE THAT FORM MOLECULES AND DONT CONDUCT ELECTRICITY. THEY ARE CALLED NONELECTROLYTES.
CONCENTRATION OF SOLUTIONS
1. THE AMOUNT OF CONCENTRATION IS HOW MUCH SOLUTE IS DISSOLVED IN GIVEN AMOUNT OF SOLVENT.
2. THE MOST COMMON EXPRESSION OF CONCENTRATION IS CALLED MOLARITY.
MOLARITY = MOLES OF SOLUTE
LITERS OF SOLUTION
EXAMPLE: WHAT IS THE MOLARITY OF SULFURIC ACID IF 10 GRAMS IS DISSOLVED IN 100 MILLILITERS OF WATER?
1. CONVERT WEIGHT TO MOLES AND MILLILITERS TO LITERS.
10 GRAMS x 1 MOLE/98.1 GMS/ MOLE(MW) = .102 MOLES
100 LM = .1L
2. PUT THE AMOUNTS IN THE FORMULA
MOLARITY = .102MOLES = 1.02 MOLAR
1L OR SOLUTION
3. ANOTHER COMMON MEASUREMENT OF CONCENTRATION IS MOLALITY.
MOLALITY = MOLES
KILOGRAMS OF SOLVENT
4. THE PROBLEMS ARE CALCULATED AS WITH MOLARITY WITH THE EXCEPTION OF WEIGHT OF SOLVENT BEING USED. NOTICE IN THE CASE OF WATER MOLARITY AND MOLALITY ARE THE SAME BECAUSE ONE LITER OF WATER WEIGHS 1 KILOGRAM.
5. ANOTHER METHOD OF CALCULATING CONCENTRATION IS CALLED MOLE FRACTION.
MOLE FRACTION = MOLES OF COMPONET
MOLES OF SOLUTION
THE COMPO9NENT BEING SOLVED FOR CAN BE EITHER SOLUTE OR SOLVENT.
MOLES OF SOLUTION IS A COMBINATION OF MOLES OF SOLUTE AND SOLVENT
EXAMPLES ARE ON PAGE 509-510
MOLE FRACTION OF SOLUTE = MOLE FRACTION OF SOLVENT ALWAYS HAS TO EQUAL 1.
FORMATION OF SOLUTIONS
1. SATURATED SOLUTIONS ARE FORMED WHEN THE SOLVENT CONTAINS THE MOST SOLUTE THAT IT CAN HOLD.
2. UNSATURATED MEANS MORE SOLUTE CAN BE ADDED TO THE SOLVENT BEFORE IT IS FULL TO CAPACITY.
3. SUPERSATURATED SOLUTIONS HAVE MORE SOLUTE THAN THE SOLVENT CAN NOLD. THESE ARE NORMALLY CREATED BY HEATING. ONCE THE SOLUTION COOLS THE SOLUTE WILL PRECIPITATE BACK OUT.
4. WHEN
SOLUTIONS FORM, BONDS ARE BROKEN BETWEEN THE SOLUTE MOLECULES AND THE SOLVENT
MOLECULES. THIS REQUIRES ENERGY TO BREAK
BONDS. THIS IS AN ENDOTHERMIC REACTION
(ENERGY GOES INTO THE REACTION). AT THE
SAME TIME BONDS ARE FORMED BETWEEN THE SOLUTE MOLECULES AND SOLVENT
MOLECULES. WHEN
5. DEPENDING ON WHICH IS GREATER THE ENDOTHERMIC ENERGY REQUIRED TO BREAK BONDS OR THE EXOTHERMIC ENERGY GIVEN OFF FROM THE FORMATION OF BONDS, DETERMINES IF THE FORMATION OF A SOLUTION WILL COOL OFF OR HEAT UP.
6. THE INTERACTION OF SOLVENT AND SOLUTE MOLECULES IS CALLED SOLAVATINO. WHEN THE SOLVENT IS WATER, IT IS CALLED HYDRATION.
BONDING IN SOLUTION FORMATION
Va C1 Na C1
BOND BOND
5O---5+H H5+ these bonds must be
broken
requires ENERGY
H H ---- O
5+ 5+ 5-
BROKEN
Na ---
C1
BROKEN
O - H H
H H O BROKEN
When bonds form,
O Na+ H H ENERGY is given off
H C1-1 H O
SOLUBILITY
1. SOLUBILITY IS THE AMOUNT OF SOLUTE THAT WILL DISSOLVE IN A SPECIFIC SOLVENT UNDER GIVEN CONDITIONS.
2. THE FACTORS DETERMINING SOLUBILITY ARE:
A. THE NATURE OF THE SOLUTE AND SOLVENT
B. TEMPERATURE
C. PRESSURE (FOR GASES)
3. THE GENERAL RULE FOR THE NATURE OF SOLUTE AND SOLVENTS IS LIKES DISSOLVE IN LIKES.
POLAR AND IONIC DISSOLVE IN POLAR (H2O IS A GOOD EXAMPLE)
NONPOLAR IN NONPOLAR (ORGANIC SUBSTANCES)
4. TEMERATURE EFFECTS GASES AND MOST WITH RAISED TEMPETATURE THERE IS MORE MOLECULAR MOTION. THEREFORE, GASES ARE LESS SOLUABLE HAD HIGHER TEMPERATURES (CARBONATION IN POP), WITH SOLIDS IT VARIES DEPENDING IF THE SOLUTION IN ENDOTHERMIC (NEEDED HEAT TO FORM) OR ENOTHERMIC (GIVE OFF HEAT IN FORMING)). IF HEAT WAS GIVEN OFF, EXTRA HEAT WOULD HURT THE SOLUBILITY.
5. PRESSURE HAS LITTLE AFFECT ON SOLID AND LIQUID IN SOLUTION. HOWEVER, GAS SOLUBILITY IS GREATLY INCREASED UNDER PRESSURE, (POP, NITROGEN IN THE BLOOD THE BENDS ARE EXAMPLES).
RATE OF DISSOLVING
1. THE AMOUNT OF SURFACE AREA. IF THERE IS MORE SURFACE TO REACT, IT WILL REACT FASTER.
2. STIRRING INCREASES SURFACE AREA CONTACT.
3. TEMPERATURE INCREASES SPEEDS UP MOLECULES AND CAUSING MORE CONTACT AS WELL AS GIVEN ENOUGH ENERGY TO REMOVE PARTICLES FROM THE SOLUTE.
COLLIGATIVE PROPERTIES
1. PROPERTIES THAT ARE DETERMINED BY THE CONCENTRATION OF SOLUTE BUT IS INDEPENDENT OF THE TYPE OF SOLUTE ARE CALLED COLLIGATIVE PROPERTIES
2. LIQUIDES EXERT A PRESSURE ABOVE THEIR SURFACE DO TO THE LIQUID MOLECULES EVAPORATING AND TURNING RO A GAS. THE MORE A LIQUID TENDS TO TURN TO VAPOR (THE MORE VOLATILE IT IS) THE MORE PRESSURE IT EXERTS. THIS IS CALLED VAPOR PRESSURE. BECAUSE SOLUTE MOLECULES REDUCE THE NUMBER OF SOLVENT MOLECULES AT THE SURFACE, COLLIGATIVE PROPERTIES REDUCE VAPOR PRESSURE.
3. WHEN NONSOLVENT SUBSTANCES LIKE ANTIFREEZE ARE ADDED TO A SOLVENT LIKE WATER THE VAPOR PRESSURE IS LOWERED. THEREFORE, SINCE THERE IS LESS TENDENCY TO TURN TO A GAS, THE BOILING POINT OF WATER IS ELEVATED.
4. THE RAISE IN ELEVATION OF THE BOILING POINT IS DIRECTLY RELATED TO THE AMOUNT OF SOLUTE WHICH CAN BE MEASURED BY MOLARITY.
THUS THE CHANGE OF BOILING POINT CAN BE CALCULATED BY MULTIPLYING A CONSTANT FOR THE SOLUTION BY THE MOLALITY OF THE SOLUTION.
T = KB x m T
= CHANGE IN TEMPERATURE
K = CONSTANT
m = MOLALITY
5. FREEZING POINTS DEPRESION ALSO HAPPENS WHEN SOLUTE MOLECULES INTERFERE WITH THE SOLVENT MOLECULES COMING TOGETHER TO FORM A SOLID. THIS LIKEWISE IS DIRECTLY RELATED TO CONCENTRATION AND CAN BE CALCULATED BY USING MOLALITY.
T =Kf x m
6. ELECTROLYTES ARE MULTIPLIED BY THE NUMBER OF PARTICLES THAT THEY FORM. Example: NaC1 FROMS Na+ & C1- IONS OR PARTICLES. THEREFORE, THE ANSWER IS MULTIPLIED BY 2.