CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito Intramolecular forces are forces that hold atoms ions together in molecules 3 Responsible for boiling pts and melting pts 4 Responsible for the heat of vaporization Hvap heat of fusion Hfus and heat of Chapter 11 11 2 Know what intermolecular forces are 1 Attractive forces that exist between molecules 2 Weaker than intramolecular forces Know the different types of intermolecular forces sublimation Hsub 1 Ion ion forces 2 dipole dipole forces 3 ion dipole forces 4 ion induced dipole forces 5 dipole induced dipole forces 6 induced dipole induced dipole forces 7 hydrogen bonding Know what factors affect the different types of intermolecular forces 1 Ion ion forces exist between ionic molecules ex forces between KF molecules 1 CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito depend on net ionic charge and size forces increase as the ionic charge increases and decrease as ionic radius increase largest ionic radius exists in the bottom most left corner of the periodic table 2 Dipole dipole forces exist between polar covalent molecules SO2 for example depend on the dipole moments of molecules dipole dipole forces increase w increasing dipole moments 3 Ion dipole forces exist between ionic molecules or ions and polar covalent molecules ex forces between NaCl and H2O depends on ionic charge and size depends on dipole moment of the polar molecules 4 Ion induced Dipole forces exist between ions and nonpolar molecules ex forces that exist between Na and depend on the charge and size of the ions largest ionic radius exists in the bottom most left corner of the periodic table depends on the polarizability of the nonpolar molecule polarizablilty increases with increase in number of electrons or molecular benzene weight 2 CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito 5 Dipole Induced Dipole Forces exist between polar molecules and nonpolar molecules ex SO2 and CH4 depend on the dipole moment of polar molecules depend on the polarizability of the nonpolar molecules 6 Induced dipole induced dipole forces Dispersion Forces exist between atoms molecules as a result of induced dipoles on them ex forces between He atoms or CH4 molecules Cl2 and CCl4 molecules etc exist everywhere increase w an increase in molecular weight of electrons 7 Hydrogen Bonding special type of dipole dipole interaction exist between hydrogen atoms in a polar bond such as N H O H and F H ex forces between HF and H2O depend on the interaction between the electrons on the electronegative atom and H Intermolecular forces give rise to a variety of properties of liquids Boiling pt stronger IMF increases the BP Surface Tension Stronger IMF higher the surface tension Viscosity stronger IMF increases viscosity viscosity decreases w increase in temperature think about syrup in a microwave 3 CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito Know how to determine what types of intermolecular forces are present within Non polar Non polar Dispersion forces or induced dipole induced dipole molecules Polar Polar Dipole Dipole Non polar Polar Dipole induced Dipole H O N or F Hydrogen bonds Ion Ion Ionic bonding forces Ion Polar Ion Dipole Ion Nonpolar Ion induced Dipole just remember polar dipole nonpolar induced dipole ion ion Know how many hydrogen bonds water has Water contains 2 hydrogen bonds but can form up to 4 from one water molecule interacting with other water molecules it is associated with 4 H bonds Know what solubility is Solubility A measure of how much solute can dissolve in a specific solvent at a specific temperature Remember that like dissolves like Know what miscibility is 4 11 3 12 3 CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito Miscibility the ability of 2 or more liquids to dissolve mix homogeneously any proportion ex ethanol and water Know how to predict the solubility of different solutes in solvents Like dissolves like 2 substances with similar intermolecular forces are likely to be soluble in each other polar solutes dissolve in polar solvents much nicer than nonpolar solvents makes obvious sense nonpolar solutes dissolve best in nonpolar solutes obvious 13 5 Know what a mechanism is Mechanism a set of elementary steps every reaction has one Know how to use elementary steps to determine the overall reaction Elementary steps in these are species called intermediates intermediates are compounds that cancel out the end of the reaction they are not found in the balanced equation Formed in the first step found in the products used in the last step found in the reactants 5 CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito Example Intermediate in the above example is IO The stoichiometry of the reactants in the RDS determines the rate law A products rate k A A B products rate k A B 2A products rate k A 2 Know what molecularity of an elementary step is and be able to determine it Unimolecular 1 molecule reacting in the reactants Bimolecular 2 molecules reacting 2 molecules found in reactants Termolecular 3 or more molecules reacting 3 or more molecules found in reactants Know what an intermediate is and be able to recognize it in a reaction Intermediates are compounds that cancel out at the end They are formed in the 1st step and are used up in the last step They are not found in the overall balanced reaction 6 CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito Be able to use RDS to determine the rate law of a reaction RDS is always the slowest step Use reactants of the RDS to determine the rate law Understand the energy diagram of different elementary steps Be able to use the diagram to determine the RDS The highest Ea the slowest step it makes sense if you think about it 7 CHM1046 FINAL EXAM STUDY GUIDE Credit to Stephen J Esposito 13 6 Know what the role of a catalyst is consumed and then reformed Catalyst substance that increases the rate of a chemical reaction The catalyst is always reacts in step 1 of reaction then reforms in the last step it is not included in the balanced equation since the catalyst is in the RDS it often appears in the rate law the presence of a catalyst does not affect the net energy difference between the reactants and the products Catalysts decrease the Ea in a reaction allowing for the reaction to progress faster Know how to find a catalyst in a reaction It is always consumed then reforms and it is NOT included in the balanced equation Know how the Ea changes in the
View Full Document
Unlocking...