Chemistry of solutions
Upcoming SlideShare
Loading in...5
×
 

Chemistry of solutions

on

  • 4,458 views

Chem :))

Chem :))

Statistics

Views

Total Views
4,458
Views on SlideShare
4,457
Embed Views
1

Actions

Likes
6
Downloads
272
Comments
0

1 Embed 1

http://www.docseek.net 1

Accessibility

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Chemistry of solutions Chemistry of solutions Presentation Transcript

  • D’ CHEMISTRY OF
    SOLUTIONS
  • SOME DEFINITIONS
    A solution is a _______________ mixture of 2 or more substances in a single phase.
    One constituent is usually regarded as the SOLVENTand the others as SOLUTES.
  • SOME DEFINITIONS
    • Solutions 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
    O2
    N2
    NH3
    H2O
    H2O
    Isopropyl alcohol
    H2O
    Ethyl alcohol
    Iodine
    Alcohol
    H2O
    Salt
  • WHICH IS WHICH 1st ROUND
    • Identify 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 ROUND
    • Identify 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
  • SOME EXAMPLES OF SOLUTION
    Air
    Oxygen
    Nitrogen
    H2O
    CO2
    Soda water
    H2O
    Vinegar
    Acetic acid
    H2O
    Sugar
    Sugar syrup
    Ag
    Hg
    Dental
    amalgam
    Brass or
    Steel
    Carbon
    Zinc
    Iron
    Copper
  • D’ UNIVERSAL SOLVENT
    WATER
    H2O
  • HOW SOLUTIONS ARE
    FORMED?
  • DEFINE SOLUTIONS
    • Solutions are homogeneous mixtures of two or more pure substances.
    • In a solution, the solute is dispersed uniformly throughout the solvent.
  • How Does a Solution Form?
    Solvent molecules attracted to surface ions.
    Each ion is surrounded by solvent molecules.
    Enthalpy (DH) changes with each interaction
    broken or formed.
    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?
  • KINDS OF SOLUTION
    • Dilute
    small amount of solute dispersed in the solvent
    • Concentrated
    large amount of solute is dissolved in the solvent
  • Types of Solutions Based on Solute Concentration…
    • Hypotonic
    (lower solute concentration) to the solution
    • Hypertonic
    (higher solute concentration) to the solution
    • Isotonicsolutions are equal in their solute concentrations. We say that they
    are isotonic to each other.
    Types of Solutions Based on Solute Concentration…
  • QUESTIONS THAT NEEDS SOLUTIONS…
    • How does a solid dissolve into a liquid?
    • What ‘drives’ the dissolution process?
    • What are the energetics of dissolution?
  • WHAT IS DISSOLUTION ?
    is the process by which a solid, 
    liquid or gas 
    forms a solution 
    in a solvent.
  • DISSOLUTION PROCESS IN SOLIDS…
    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 LIQUIDS & GASES…
    For liquids and gases, the molecules must be compatible with those of the solvent for a solution to form.
  • dry
    Dissolution vs Reaction
    NiCl2(s)
    Ni(s) + HCl (aq)
    NiCl2(aq) + H2(g)
    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.
  • DEFINE
    SOLUBILITY?
  • 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
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    SOLUBLE
    SOLUBLE
    INSOLUBLE
    S/SOLUBLE
    SOLUBLE
    SOLUBLE
    INSOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
    INSOLUBLE
    INSOLUBLE
    SOLUBLE
    S/SOLUBLE
  • VOCABULARY
    • Immiscible
    Two liquids that are insoluble
    (Oil & Vinegar)
    • Miscible
    Two liquids that are soluble in each other
    (Alcohol & Water)
    IMMISCIBLE
    MISCIBLE
    MISCIBLE
    S/MISCIBLE
    • Saturated solution
    • Solvent 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
  • Degree of Saturation
    • Unsaturated Solution
    • Less 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.
  • FACTORS AFFECTING
    SOLUBILITY
  • 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
    IMMISCIBLE
    MISCIBLE
    MISCIBLE
    S/MISCIBLE
    SOLUBLE
    SOLUBLE
    INSOLUBLE
    INSOLUBLE
  • Temperature
    Generally, the solubility of solid solutes in liquid solvents increases with increasing temperature.
  • LABORATORY ACTIVITY 2.8FACTORS SOLUBILITY
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
  • Temperature
    • The 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
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
    TAKES TIME
    TO DISSOLVE
    EASILY
    DISSOLVED
  • 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
    DISSOLVES
    FASTER
    TAKES TIME
    DISSOLVES
    DISSOLVES
    FASTER
    TAKES TIME
    DISSOLVES
  • Factors Affecting Solubility
    The stronger the intermolecular attractions between solute and solvent, the more likely the solute will dissolve.
    Example: ethanol in water
    Ethanol = 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?
    HEALTHAPPLICATION
  • 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 Law
    States that:
  • 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;
    Pgis the partial pressure of the gas above the liquid.