CHEM 1120 1st Edition Lecture 1 Outline of Last Lecture I No previous lecture Outline of Current Lecture II Intermolecular Forces A 6 Types of Intermolecular Forces IMFs III Introduction to Chapter 13 The Solution Process A Solution Terms Homogeneous Solute vs Solvent etc B Intermolecular Interactions Involved in Solution Formation IV Dissolution process V Solubility Current Lecture II A Before we can talk about chapter 13 and forming solutions we must remember the different types of IMFs forces acting between molecules because the ability to form solutions depends on the IMFs involved in the process These IMFs in order from strongest to weakest are 1 Ion Dipole force between an ion and a polar molecule possessing a permanent dipole moment 2 Hydrogen Bonding force resulting from attractions between molecules with a hydrogen bonded to an electronegative element most common OH HF NH 3 Dipole Dipole force when polar molecules interact or become close positive end of one approaches negative end of another 4 Ion Induced Dipole weak attraction resulting from an ion influencing a dipole in an atom or nonpolar molecule by disturbing their electron arrangement These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 5 Dipole Induced Dipole weak attraction resulting from a polar molecule influencing a dipole in an atom or nonpolar molecule by disturbing their electron arrangement 6 Dispersion Forces forces resulting from induced dipoles attracting each other III A Homogeneous the same content throughout the solution or mixture Solution homogeneous mixture of two or more substances Solute the dissolved material usually least abundant in solution Solvent the dissolving agent usually most abundant in solution Solvation when solvent molecules array around a solute particle Hydration when water solvent molecules array around a solute particle solvation where water is the solvent B In solution formation certain intermolecular interactions are involved depending on whether they happen between a solute and another solute a solute and a solvent or a solvent and another solvent 1 Solute Solute these interactions must be overcome to allow the solute to spread through the solvent 2 Solute Solvent interactions that happen as these different particles mix together 3 Solvent Solvent these interactions must be overcome to allow room or holes for the solute to spread through For Gas and Solid Solutions 1 Gas Gas all gases are infinitely soluble in each other 2 Gas Solid Gases dissolve in solids by occupying holes in the crystalline structures 3 Solid solid Atoms may replace atoms or fill in holes in the crystalline structures IV The process of dissolution or dissolving a solute into a solvent can be viewed as a three step process Example Dissolving NaCl in Water Step 1 The NaCl crystals are separated into ions endothermic requires work change in HSOLUTE is positive Step 2 The water molecules separate to create holes that can accommodate the Na and the Cl ions endothermic requires work change in HSOLVENT is positive Step 3 The Na and Cl ions enter and fill the holes created by the water molecules exothermic work is done by system change in HMIX is negative Heat of Solution HSOLUTE HSOLVENT HMIX Processes in which entropy increases tend to be spontaneous and vice versa Things will try to be as disordered as they can be with the energy they have V Solubility the maximum amount of solute that dissolves in a given amount of solvent at a certain temperature when at equilibrium Unsaturated solution where there is less solute than can dissolve in the solvent Saturated solution where the solvent holds as much solute as is possible at a certain temperature dissolved solute is in dynamic equilibrium with solid solute particles Supersaturated solution where the solvent holds more solute than an equivalent saturated solution Overall the general trend shows that the stronger the attractions between solute and solvent molecules the greater the solubility of the solute in that solvent Additionally polarity comes into play when talking about the attractions and solubility because polar solutes tend to dissolve in polar solvents and nonpolar solutes tend to dissolve in nonpolar solvents These tendencies bring us to the conclusion that polar solutes tend not to dissolve or tend to be insoluble in nonpolar solvents and nonpolar solutes tend to be insoluble in polar solvents