SOLUBILITY. Solubility Solubility how many grams of solute that will dissolve in 100 g of solvent to...
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Transcript of SOLUBILITY. Solubility Solubility how many grams of solute that will dissolve in 100 g of solvent to...
SOLUBILITY
SolubilitySolubilitySolubility
how many grams of solute that will dissolve in 100 g of solvent to make it saturated at a given temperature
Dissolution- the rate at which a substance dissolves
FACTORS AFFECTING SOLUBILITY
Polarity
Factors Affecting Solubility
Temperature
Surface Area
Stirring
Pressure
Particle size – area of solute particles exposed to the action of the solvent particles. Increase in surface area of the solute particles , solubility increases
Example: fine table salt dissolves faster than rock salt
SURFACE AREA
Stirring or Agitation increases the solubility of solid solute particles in a solvent. Because it speeds up the contact between the surface of the solute and the solvent particles
AGITATION
Effect of Temperature on Solubility of Solids and Liquids
• Generally, increasing the temperature will increase solubility of solids and liquids.
• Application of heat - solvent molecules move faster and come in contact frequently with the solute particles, increasing solubility.
Solubility Curves
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517
0 10 20 30 40 50 60 70 80 90 100
Solubility vs. Temperature
Sol
ubili
ty (
gram
s of
sol
ute/
100
g H
2O)
KI
KCl
20
10
30
40
50
60
70
80
90
110
120
130
140
100
NaNO3
KNO3
HCl NH4Cl
NH3
NaCl KClO3
SO2
shows the dependence
of solubility on temperature
gases
solids
But increasing temperature will lower the solubility of gases (the gas will escape from solution, going back to the gas phase).
Effect of Temperature on Solubility of Solids and Liquids
Figure 13.18
To
Sol.
To
Sol.
Solids dissolved in liquids Gases dissolved in liquids
As To , solubility As To , solubility
• Thermal pollution: if lakes get too warm, CO2 and O2 become less soluble and are not available for plants or animals.
• Warm Pop
Making ConnectionsMaking Connections
The Effect of Pressure on the Solubility of Gases
• Pressure has no effect on the solubility of solids and liquids but has a strong effect on the solubility of gases.
• The solubility of gases increases when the pressure above the gas is increased. In other words, more gas will dissolve when pressure is increased. This is known as HENRY’S LAW (William Henry, English chemist).
Pressure Effects
Figure 13.14: Factors Affecting SolubilityFigure 13.14: Factors Affecting Solubility
Henry’s Law
Sg = 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.
• Nitrogen narcosis, the “bends” • Soda
Making ConnectionsMaking Connections
http://www.youtube.com/watch?v=LfCOnGHheok&feature=fvst
Solutions
How does a solid dissolve into a liquid?
What ‘drives’ the dissolution process?
Polarity Solute – Solvent Interactions
• Intramolecular Bonding
• Intermolecular Bonding
Intramolecular Bonding
• Intramolecular bonding refers to the chemical bonding that holds atoms together within a molecule of a compound
Covalent bonding and ionic bonding are the two main types of intramolecular bonding
• Ionic bonding involves the transfer of valence electrons from one atom to another.
• The electrostatic attraction between opposite charged ions holds the molecule (formula unit) together. An example is sodium chloride, NaCl, which involves the attraction between Na+ and Cl- ions.
IONIC BONDING
Covalent bonding involves the sharing of valence electrons between two atoms. Eg. covalent bonding holds hydrogen and oxygen atoms together to form a water molecule, H2O.
POLAR- unequal sharing of electronsNON POLAR – equal sharing of electrons
COVALENT BONDING
NON POLAR MOLECULE
• Nonpolar molecules either have no positive and negative ends, because the bonds making up the molecule are nonpolar, or because the entire outer "edge" is negative while the core of the molecule is positive (or vice versa), thus having no oppositely charged ends.
POLAR MOLECULE
• A polar molecule will have one end of the molecule bearing a partial positive charge while another end carries a partial negative charge. Polar molecules must contain polar bonds.
The oxygen end of the molecule has a partial negative charge (δ-), while the hydrogen end is partially positive (δ+).
Intermolecular Bonds occur between molecules
How Does a Solution Form?Solvent molecules cluster around the solute particles. If the intermolecular attraction between the solvent and solute is stronger than between the solute –solute or solvent-solvent molecules, then a solution forms.
“like dissolves like”Two substances with similar intermolecular forces are likely to be soluble in each other.
• non-polar molecules are soluble in non-polar solvents
CCl4 in C6H6
• polar molecules are soluble in polar solvents
C2H5OH in H2O
• ionic compounds are more soluble in polar solvents
NaCl in H2O or NH3 (l)
12.2
SOLUTE POLAR SOLVENT
NONPOLAR SOLVENT
Ionic Soluble Insoluble
Polar Soluble Insoluble
Nonpolar Insoluble soluble
Vitamins• Water Soluble
– Vitamin C– Must be replenished regularly
• Fat Soluble– Can overdose (liver damage,
hair loss, blurred vision, numbness)
– Vitamin A– Can be ingested periodically,
stored in body fat
Making ConnectionsMaking Connections
Factors Affecting Solubility• Vitamin A is soluble in nonpolar compounds (like
fats).• Vitamin C is soluble in water.
Watch video and write down explanation on sheet provided.
How Salt Dissolves? ION-POLE ATTRACTION
How Salt Dissolves? ION-POLE ATTRACTION
• Each ion in the solute is surrounded by the partial positive and negative solvent molecules in the water.
• Solute is pulled out of its lattice and solvent molecules spread the solute out throughout the solution.