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Liquid

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Liquid

  1. 1. LIQUID
  2. 2. Introduction <ul><li>Molecules in liquid are closed to one another, attractive forces are stronger (keep molecules together) compared to gases. </li></ul><ul><li>Can move past one another freely (flow, poured) </li></ul><ul><li>Take the shape of a container. </li></ul><ul><li>Almost incompressible </li></ul><ul><li>Viscosity (its resistance to flow) – is affected by size & intermolecular forces. </li></ul><ul><li>Complex, polar molecules: have high viscosity. </li></ul><ul><li>Increase T  viscosity will decrease </li></ul>
  3. 3. Mercury is viscous liquid
  4. 4. <ul><li>Surface tension : force that cause the surface area of liquid to contract (responsible for spherical shape of liquid drop). </li></ul><ul><li>Molecule that have a high surface tension is………….? </li></ul><ul><li>Decrease with an increase in temp. or decrease in polarity. </li></ul><ul><ul><li>Cohesive : intermolecular forces holding a liquid together. </li></ul></ul><ul><ul><li>Adhesive forces : forces of attraction between a liquid and surface. </li></ul></ul><ul><li>Diffusion – Spreading of liquid or gas into a region where it is originally not present. </li></ul><ul><li>Liquid diffuses slower compare to the gas (stronger force between molecules). </li></ul>
  5. 5. <ul><li>Liqui d Vapour </li></ul><ul><li>Vaporization – change of liquid to gas. A few high-energy molecules which possess sufficient energy to overcome the attractive forces and escape from the bulk liquid (convert to gas). </li></ul><ul><li>Condensation : conversion of a gas or vapour to liquid. A fraction of gaseous molecules lose energy and return to liquid state. </li></ul><ul><li>Liquid in an equilibrium state : rate of vaporization = rate of condensation </li></ul>vaporization condensation
  6. 6. <ul><li>Vapour Pressure – pressure exerted at the equilibrium state of a liquid </li></ul><ul><li>Affected by its intermolecular forces and temperature. </li></ul><ul><li>1) intermolecular forces : </li></ul><ul><ul><li>Vapour pressure high if intermolecular forces are weaker </li></ul></ul><ul><ul><li>Weaker intermolecular forces  more volatile  low boiling point </li></ul></ul><ul><ul><li>Stronger intermolecular forces  non volatile  higher boiling point </li></ul></ul><ul><ul><li>2) Temperature : Vapour pressure increase if temp. increase (rate of motion increase). </li></ul></ul>
  7. 7. Boiling of liquids <ul><li>Process in which vaporization occurs throughout a liquid. </li></ul><ul><li>Boiling point = temperature at which the vapour pressure is equal to external atmospheric pressure. </li></ul><ul><ul><li>Not constant, depend on the atmospheric pressure and the nature of the attractive force between the liquid molecules. </li></ul></ul><ul><ul><li>Higher atmospheric pressure : boiling point increase. </li></ul></ul><ul><ul><li>Stronger intermolecular forces (or polar liquids) => higher boiling point. </li></ul></ul><ul><li>Normal boiling point = temperature at which the vapour pressure is equal to 1 atm. </li></ul>
  8. 9. Introduction <ul><li>Particles are closely arranged and touch one another – can only vibrate in a fixed position (fixed volume, shape and incompressible). </li></ul><ul><li>Has high density. </li></ul><ul><li>Divided into crystalline solid and amorphous solid </li></ul><ul><li>crystalline solid have a regular three-dimensional arrangement, occupy fixed position. e.g.. NaCl </li></ul><ul><li>amorphous solid have random arrangement or un orderly arrangement e.g. rubber & plastics </li></ul>
  9. 10. Phase Changes in Solid <ul><li>Heating – particles vibrates and solid melts (enough energy to break away from interparticle forces. </li></ul><ul><li>Molecules move freely ( Solid Liquid). </li></ul><ul><ul><li>Melting point : temp. at which the solid and liquid phase coexist in equilibrium. </li></ul></ul><ul><ul><li>Freezing point : the temp. at which the liquid and solid phase coexist in equilibrium. </li></ul></ul><ul><ul><li>Cooling – particles of liquid lose energy, move closer and arrange to fixed position. (Liquid Solid). </li></ul></ul>
  10. 11. <ul><li>Sublimation – direct transformation of solid into gas, without going through liquid phase. </li></ul><ul><li>Deposition – direct transformation from gas into solid during a cooling process. </li></ul>
  11. 12. <ul><ul><li>TYPE OF SOLIDS </li></ul></ul><ul><ul><li>Ionic solids </li></ul></ul><ul><ul><li>particles made up of cation and anion respectively, which are alternatively arranged in three dimensions and are held strongly by electrostatic forces ;eg NaCl </li></ul></ul><ul><ul><li>Giant covalent solids (Macromolecule crystals) </li></ul></ul><ul><ul><li>consist of particles held together by covalent bonds , non- metals. e.g.. Graphite, diamond, silicon. </li></ul></ul><ul><ul><li>Molecular covalent solids </li></ul></ul><ul><ul><li>particle consists of simple molecules which are held together by weak van der Waals forces (Has very low melting and boiling point). e.g.. I 2 and P 4 . </li></ul></ul><ul><ul><li>Metallic solids </li></ul></ul><ul><ul><li>atoms of the same metal which are bound together by metallic bond (strong force of attraction between the positive ions and delocalized electrons). e.g.. Iron and titanium. </li></ul></ul>
  12. 13. <ul><li>Gas Laws </li></ul><ul><li>Boyle,s Law P 1 V 1 = P 2 V 2 </li></ul><ul><li>Charles's Law V 1 /T 1 = V 2 /T 2 </li></ul><ul><li>Avogadro's Law V 1 /n 1 = V 2 /n 2 </li></ul><ul><li>Ideal gas equation PV = nRT </li></ul><ul><li>Combined gas Law P 1 V 1 / T 1 = P 2 V 2 / T 2 </li></ul>SUMMARY
  13. 14. <ul><li>Dalton’s Law of partial pressure </li></ul><ul><ul><ul><li>P Total = P 1 + P 2 + P 3 +P 4 + …….+P n </li></ul></ul></ul><ul><li>= (n X + n y + n z ) (RT) </li></ul><ul><li> V </li></ul><ul><li>Mole fraction of gas : X x = n x /n total = P x /P total </li></ul><ul><li>van der Waals equation </li></ul><ul><li>P + n 2 a (V- nb) = nRT </li></ul><ul><li> V 2 </li></ul>

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