Chem 1120 1st Edition Exam 1 Study Guide Lectures 1 12 Lecture 1 January 21 What are the 6 different types of intermolecular forces and describe each Ion Dipole force between ion and polar molecule with dipole moment Hydrogen Bonding force from attractions between molecules with H bonded to electronegative element OH HF NH etc Dipole Dipole polar molecules interact or become close Ion Induced Dipole weak force from ion inducing dipole in an atom or nonpolar molecule Dipole Induced Dipole weak force from polar molecule influencing dipole in atom or nonpolar molecule Dispersion Forces forces from induced dipoles attracting each other Explain the differences between a solute and a solvent and saturated vs unsaturated vs supersaturated Solute is the dissolved material solvent is the dissolving agent saturated is when a solution s solvent holds as much solute as is possible dissolved solute in equilibrium with solid solute particles unsaturated is when there is less solute than can be dissolved in a solution and supersaturated is when the solution s solvent holds more solute than a saturated solution Describe the process of dissolution 3 steps 1 crystals separate into ions endothermic 2 water molecules separate to create holes to accommodate ions endothermic 3 ions fill the holes created by the water molecules exothermic Heat of Solution HSOLUTE HSOLVENT HMIX Lecture 2 January 23 Describe the idea of entropy Entropy is a thermodynamic measure of the randomness or disorder of a system In our world we assume objects move from a higher energy level toward a lower energy level and the same is true for chemical processes Most release more heat than they absorb making them exothermic although some can be endothermic When entropy increases the reaction is spontaneous and vice versa Name the five different concentration units and know how to complete problems for each including ppm ppb and vapor pressure lowering Molarity M moles solute Liters solution Molality m moles solute kg of solvent Mass percent m component A mass of A total mass of solution X 100 Volume percent v component A V of A total V of solution X 100 Mole Fraction X moles of A total moles of solution ppm mass A total mass X 10 6 ppb mass A total mass X 10 9 Vapor pressure lowering PSOLUTION XSOLVENT POSOLVENT Example How many grams of glucose C6H12O6 must be dissolved in 552 grams of water at 20 degrees C v p 17 5 torr to lower its vapor pressure by 2 0 torr Solution The change in PSOLUTION 2 0 torr so 15 5 torr XWATER x 17 5 torr molar masses 180 1559 g mol and 18 02 g mol 552 g water 18 02 g mol 30 64 mol water XWATER 15 5torr 17 5 torr 30 64 mol water 30 64mol water mol glucose mol glucose 3 953 3 953 mol glucose x 180 1559 g mol 712 3 g glucose Lecture 3 January 26 Give the freezing point lowering and boiling point elevation equations and know how to use each what each component of the equations mean Tf ikf m i van t hoff factor 2 when a substance ionizes usually 1 Tb ikb m stants m molality kb and kf boiling and freezing molal con Example Vinegar is essentially a 5 0 w w solution of acetic acid HC2H3O2 in water What is the freezing point of vinegar kf 3 90 acetic acid 1 86 water units degrees C m Solution Assume 1 kg of solution 0 95 kg water 0 05 kg 50 g acetic acid 50 g 60 05g mol 0 8326 mol acetic acid molality 0 8326 mol 0 95 kg 0 8764 m Tf ikf m 1 86 0 8764 1 63 degrees C Describe osmosis give the osmotic pressure equation and know how to apply this equation as well as what each component of the equation means Osmosis is the diffusion of a solvent usually water through a semi permeable membrane into a solution Osmotic pressure is the pressure resulting from osmosis and equal to the minimum counter pressure necessary to prevent osmosis MRT M Molarity R 0 08206 T Kelvin Lecture 4 January 28 Explain how to find the van t Hoff factor and why the actual values are slightly different than the expected ones To find the van t Hoff factor is pretty simple It is equal to the moles of solute dissolved in a solution For salts you just take the number of ions over the formula units NaCl splits into two ions therefore the van t Hoff factor is two The van t Hoff factor usually ends up as 1 or 2 depending on if it dissolves into ions or not Acknowledge the difference between a colloid and a suspension and discuss hydrophilic vs hydrophobic colloids A suspension is a heterogeneous mixture with dispersed particles larger enough to be seen and a colloid is a mixture with dispersed particles larger than a solution s but smaller than a suspension s For a hydrophilic colloid the surface is hydrophilic while the core may be hydrophobic The surface groups bond to water and they are large molecules For a hydrophobic colloid it must be stabilized by absorbed ions on the surface and these ab sorbed ions interact with water and particles repel each other The tail is hydrophobic while the head is polar Lecture 5 January 30 For a generic reaction describe how to find the rate law due to concentration and the rates of each reactant and product mathematically In most cases for a generic reaction aA bB cC dD the rate law due to concentration looks like Rate k A m B n Show the equations for average rate and instantaneous rate and also show how to find the units of a rate giving the units for first and second order rates average rate A t instantaneous rate slope of the tangent to the curve rate at an arbitrarily short time Units of rate units of rate constant units of concentration order 1st order rate units s 1 2nd order rate units M 1 s 1 Lecture 6 February 2 Explain the process of finding reaction order when given a set of data Additionally make a table of all the reaction orders and their corresponding units rate laws half life equations etc When given a set of data see where a set of concentrations doubles triples quadruples etc and then look at the corresponding rate constants Compare the ratio of how the concentrations change and how the rate laws change at the same time If the ratio is 1 1 then the reaction is first order If the ratio is not affected by a concentration then the order with respect to that reactant is zero If the ratio is squared then it is second order Rate Law Units For k Integrated Rate Law Straight Line Plot Half Life Zero Order r k M s A t kt A o A t vs t First Order r k A s 1 ln A t kt A o ln A t vs t 0 693 k Second Order r k A 2 M …