CHEM 1120 1nd Edition Lecture 2 Outline of Last Lecture I. Syllabus OverviewOutline of Current Lecture II. Intro to ChapterIII. Intermolecular forcesa. Difference between intermolecular and intramolecular forcesb. 6 types of intermolecular forcesc. Gas and Solid solutionsd. Why do substances dissolve?IV. Heat of Solutiona. Equation: Heat of solute + Heat of solvent + Heat of mixingV. The Solution Process and Entropya. Why not all processes are exothermicb. Saturated, unsaturated, and supersaturated solutionsCurrent LectureI. Intro to Chaptera. Does NOT have to be a liquid to be a solutionb. Solvent-most of solution, what substance is being dissolved inc. Solute-least of solution, what is being dissolvedd. How does a solution form? Solvent pulls solute particles apart (Called solvating)e. Competition between whether it wants to be dissolved or if it wants to stay with the crystal, can go back and forthf. At equilibrium-no ions come back to the solidII. Intermolecular Forcesa. Intermolecular: between DIFFERENT moleculesb. Intramolecular: within a SINGLE moleculec. Solution of A and B will form ONLY if A-B attractions are comparable in strength to A-A and B-B attractionsi. If not, they won’t mix (i.e. Water and oil)d. Attractive forces between the solute and solvent can be VERY STRONGi. i.e.-Melting point of NaCl is 801 degrees C, but water will dissolve it at room tempii. When solvent is water, called hydrationThese 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.e. 6 types of intermolecular forcesi. Ion-dipole, strongest (40-600-Measured in kJ/mol), Na+, H2O1. Ion and dipole interactii. Hydrogen bonding (10-40), CH3OH/H2O1. Hydrogen bonds to N, O, Fiii. Dipole-dipole (5-25), PH3/H2O1. 2 dipoles interactingiv. Ion-Induced Dipole (3-15), Fe2+, O2 (in blood)1. Bring a charge next to something that doesn’t have a dipole, causes it to become a dipole. Take charge away, dipole will go away.2. Less commonv. Dipole-Induced dipole (2-10), H2O/O21. Less common2. Similar to ion-inducedvi. Dispersion Forces (.05-40), C8H18/C6H141. At an instantaneous point, molecule has a chargef. Gas and Solid solutionsi. Gas-gas: infinitely soluble in each otherii. Gas-solid: gasses dissolve in solids by filling “holes”iii. Solid-solid: atoms may replace atoms (called substitutional alloys) or occupy holes (called interstitial alloys)g. Why do substances dissolve? 3 steps, dissolving NaCl in wateri. Step 1: NaCl crystals separated into ions (endothermic process, positive)1. Separating ions takes workii. Step 2: Water molecules create holes to accommodate Na+ and Cl- ions (endothermic process, positive)1. Separating the water molecules also takes workiii. Step 3: the Na+ and Cl- ions enter the holes (exothermic process, negative)III. Heat of Solutiona. Heat of solute (+) +Heat of solvent (+) + Heat of mixing (-) = Heat of solutioni. Heat of solution is NOT predictable (+ or -)ii. (Heat of solute + Heat of solvent) > (Heat of mixing), Heat of solution is +iii. (Heat of solute + heat of solvent) < (Heat of mixing), Heat of solution is –iv. Technology in heat and cold pads, mix two things, endothermic=cold pads, exothermic=heat padsIV. The Solution Process and Entropya. Naturally expect objects to move towards lower energy, MOST chemical processes (Exothermic)b. Not all chemical processes exothermici. Systems tend toward a state of higher entropy (S)ii. Covered more later in chapter 19c. Saturated solutions and solubilityi. Add more of a solute to a solvent and it dissolves=UNSATURATEDii. Add more and it crystalizes=SUPERSATURATED1. Very unstableiii. At