CHEM 1010- EXAM 3 STUDY GUIDE
CHEM 1010- EXAM 3 STUDY GUIDE General Chemistry 1010
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This 6 page Study Guide was uploaded by Jomary Arias on Sunday April 17, 2016. The Study Guide belongs to General Chemistry 1010 at Clemson University taught by Dr. Ava Kreider-Mueller in Winter 2016. Since its upload, it has received 23 views. For similar materials see General Chemistry 1 in Chemistry at Clemson University.
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Date Created: 04/17/16
CH 1010: General Chemistry Dr. Ava Kreider-Mueller EXAM 3 STUDY GUIDE CHAPTER 6: Intermolecular Forces & Attraction b/w Particles [Key Terms] Gases - particles are independent of one another, feel little attractive force, and are free to move about randomly. Liquids- particles are strongly held together by attractive forces which are strong enough to hold the particles in close contact while letting them slide over one another. Solids- the particles are held by attractive forces which hold the particles in place. Intermolecular forces- act between molecules to hold them together at certain temperatures Van der Waals forces- several different types of intermolecular forces, including dipole-dipole forces, London dispersion forces, & hydrogen bonds. Contain partial charges. Ion-dipole forces- act b/w ions and molecules Net Force- sum of many individual interactions Viscosity- measure of a liquid’s resistance to flow Surface Tension- resistance of a liquid to spread out & increase its surface area Solvent- component of solution that is present in the larger # of moles. Ex) water Solute- component in a solution other than the solvent. A solution may contain one or more solutes. Ex) NaCl Solubility- maximum quantity of a substance that can dissolve in a given volume of solution [Ion- Dipole Force] - NOT one of the Van der Waals forces - Result from interactions b/w an ion & the polar charges of a polar molecule - Contain full charges and the ion-ion attraction is so strong that they create an ionic bon [3 Types of Intermolecular Forces] 1. London Dispersion 2. Dipole-Dipole Forces 3. Hydrogen Bonds [London Dispersion] - Present in ALL atoms & molecules, regardless of structure - WEAK attractive forces CH 1010: General Chemistry Dr. Ava Kreider-Mueller EXAM 3 STUDY GUIDE - Magnitude of force depends on the ease with which a molecule’s e- cloud can be distorted by a nearby electric field - Temporary dipoles are created as the nuclei & electron clouds interact - Shape contributes to the strength - More spread-out shape (longer Hydrocarbon chains) allow greater contract b/w molecules & give rise to higher dispersion forces - Chain length ↑, the Boiling Point ↑ - The LESS compact the molecule, HIGHER the boiling point. Chains vs. Spherical shapes allow greater contact b/w molecules and give rise to higher dispersion forces Lighter atoms Heavier atoms -Less polarizable -More polarizable - Contains only a few tightly held electrons -Contains many electrons, some less tightly held -Smaller dispersion forces and farther from the nucleus -Smaller molecules -Larger dispersion forces -Larger dispersion forces [Dipole-Dipole Forces] -Experienced by NEUTRAL, but polar molecules b/c of electrical interactions among dipoles of neighboring molecules -Forces can be ATTRACTIVE or REPULSIVE, depending on orientation -Polar molecules ATTRACT, when they orient w/ UNLIKE charges close together -Polar molecules REPEL, when they orient w/ LIKE charges close together -Net force is the sum of many individual interactions. Strength depends on the size of the dipole moments involved. The more polar the substance, the greater the strength of its dipole-dipole interaction - The larger the dipole moment-> the stronger the intermolecular forces the greater the boiling point - WEAKER than ion-dipole forces [Hydrogen Bonds] Attractive interaction b/w hydrogen atoms bonded to a very electronegative atom ex) O, N, F and an electron- rich region elsewhere in the same molecules or in a different molecules O-H, N-H, and F-H are highly polar with a partial (+) charge on the hydrogen, and has a partial (-) charge on the electronegative atom CH 1010: General Chemistry Dr. Ava Kreider-Mueller EXAM 3 STUDY GUIDE Hydrogen has NO CORE e- to shield the nucleus, & it has a small size so it can be approached closely by other molecules Dipole-dipole interaction b/w hydrogen & unshared electron pair on a nearby atom is unusually strong Is the primary intermolecular force that holds large molecules together Boiling point ↑ w/ molecular weight or as you move down a group, exceptions: N3, H2O, and HF [Viscosity] Ease in which individual molecules move around when intermolecular forces are present Temperature dependent Small nonpolar molecules experience only weak intermolecular forces, & have low viscosities Larger polar substances have stronger intermolecular forces, & have higher viscosities Stronger intermolecular forces have higher boiling and melting points [Surface Tension] Resistance of a liquid to spread out & increase its surface area, caused by the difference in intermolecular forces Temperature dependent Molecules at the surface experience attractive forces only on one side Molecules in the interior are surrounded and are pulled equally in all directions Surface tension is higher in liquids that have stronger intermolecular forces. Ex) Mercury Miscible Immiscible Liquids that are mutually soluble in any Liquids that have limited solubility in each other, proportion, completely dissolves won’t dissolve “LIKE dissolved LIKE” POLAR solutes tend to dissolve in POLAR solvents NON-POLAR solutes tend to dissolve in NON-POLAR solvents Chapter 7: Stoichiometry Stiochimetry: the mole ratios among the reactants and products in a chemical reaction Chemical Equation: description of the identities and proportions of reactants and products Reactants: substances consumed CH 1010: General Chemistry Dr. Ava Kreider-Mueller EXAM 3 STUDY GUIDE Products: substances formed Molecular mass: mass of one molecule of a molecular compound Molar mass: mass of 1 mole of a substance Empirical Formula: showing the smallest whole number ratio of elements in a compound Limiting Reactant: reactant that is consumed completely in a chemical reaction Theoretical Yield: maximum amount of product possible in a chemical reaction for given quantities of a reactant [Balancing Equations] - Take an inventory of how many moles of each element are present in the given equation - Remember the Law of Conservation of Mass! - Use a ratio of coefficients to convert moles A to moles B [Limiting versus Excess reagent] 1. Convert grams to moles 2. Determine how many moles of each element are available 3. Determine how much is needed 4. Assume one as the limiting reagent [Percent Yield] -Theoretical will always be greater than Actual - Work backwards from the percent yield and Theoretical then multiply by 100 CHAPTER 8: Aqueous Solutions Molarity- number of moles of a solute per liter of solution Dilution- process of lowering the concentration of a solution by adding more M 1 M1= 2 2 Electrolyte- material that conducts electricity because it contains free ions Neutralization Reaction- takes place when an acid reacts with a base and produces a solution of a salt in water. Molecular equation: a balanced equation that describes a reaction in solution in which the reactants are written as undissociated molecules Spectator ions- ions that are uncharged by a chemical reaction Net Ionic Equation: balanced equation that describes the actual reaction taking place in a solution. Precipitate: solid product formed from a reaction in solution Titraion: analytical method for determining the concentration of a solute in a sample by reacting the solute with a solution of a known concertation CH 1010: General Chemistry Dr. Ava Kreider-Mueller EXAM 3 STUDY GUIDE WEAK ACID STRONG ACID Acid that only PARTIALLY dissociates in Acid that COMPLETELY dissociates into ions aqueous solutions in aqueous solution WEAK BASE STRONG BASE Base that PARTIALLY dissociates in aqueous Base that COMPLETELY dissociates in solution aqueous solution - Precipitate forms when the attraction b/w the cations & anions in a solution are so strong that they overcome the attractive forces of the polar water solvent - Ions w/ higher charges tend to have ↑ LE because it is difficult to break the bonds due the electrostatic interaction b/w cations and anions. CHAPTER 9: Thermochemistry Chemical Energy- potential energy stored in chemical bonds Internal Energy- sum of all the kinetics and potential energies of all the components of a system Thermodynamics- study of energy and its transformation First Law of Thermodynamics- principle that the energy gained or lost by a system must equal the energy lost or gained by the surroundings System- part of the universe that is the focus of a thermochemical study Thermal Energy- portion of the total internal energy of a system that is proportional to its absolute temperature Work (w)- distance moved times the force that opposes the motion Pressure- Volume (P-V)- work associated with the expansion or compression of a gas Enthalpy (H)- sum of the internal energy and the pressure- volume product of a system. H= E+ PV Enthalpy change (∆H)- energy absorbed by the reactants or the energy given off by the products for a reaction carried out Heat Capacity (C p- energy required to raise the temperature of an object by 1ºC at constant pressure. ENDOTHERMIC PROCESS EXOTHERMIC PROCESS Energy (heat) flows from the surroundings into Energy (heat) flows from a system into the the system surroundings CH 1010: General Chemistry Dr. Ava Kreider-Mueller EXAM 3 STUDY GUIDE ENTHALPY OF VAPORIZATION (∆H vap) ENTHALPHY OF FUSION (∆H ) fus Energy required to convert 1 mole of liquid at Energy required to convert 1 mole of solid at its boiling point into the vapor state its melting point into the liquid state - Sublimation (sg), Fusion (sl) , Vaporization (l g). This is an ENDOTHERMIC process - When breaking bonds: Energy is REQUIRED - When forming bonds: Energy is RELEASED - State functions do not depend on how a change occurs
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