Review Chapters 6 -10 : General, Organic, & Biological Chemistry Janice Gorzynski Smith Chapter 6 & 7 Concepts Energy conversions, conservation of energy Breaking bonds requires E, forming bonds releases E Endothermic & Exothermic Reactions Energy diagrams, Activation Energy, heat absorbed or released Factors affecting rates of reactions Concentration, temperature, catalysts Equilibrium Equilibrium constant expressions Le Chatlier Principle States of matter: g, l, s & their properties Effect of intermolecular forces on behavior Gas laws: combined, ideal, & dalton’s law partial pressure Intermolecular forces London-Dispersion, Dipole-Dipole, Hydrogen-Bonding Relative strength, importance in g, l, s behavior Phase Changes Navigate a heating/cooling curve Enthalpy of phase changes 2 Equations & Conversions P1V1 = T1 P2V2 K = T2 [C]c [D]d [A]a [B]b 1 cal = 4.184 J PV = nRT L • atm R = 0.0821 mol • K L • mm Hg R = 62.4 mol • K Ptotal = PA [products] [reactants] = + PB 1,000 cal = 1 kcal 1,000 J = 1 kJ + PC 1 kcal = 4.184 kJ Equations to memorize in orange Energy of Reactions ENDOTHERMIC Transition State E Energy required to break bonds Energy released as bonds form Ea Ea ENDOTHERMIC ΔH Reactants Heat + A + B C + D Products have weaker bonds and a higher energy then Reactants. Heat is absorbed by the system. ΔE + ΔH + Heat absorbed ΔH Heat released Products EXOTHERMIC EXOTHERMIC A + B C + D + heat Products have stronger bonds and a lower energy then Reactants. Heat is released by the system. ΔE - ΔH - Rates of Reactions Increase the Rate of a Reaction Increase Temperature Increase Average KE of particles, so more likely to collide with enough energy to overcome Ea Increase Concentration Reactants Increase the number of collisions per second Add a Catalyst Decrease Ea Greater likelyhood that particles will have enough KE to react Same likelyhood rxn will happen when particles collide, but more collisions Equilibrium & Le Chatlier’s Principle aA + bB equilibrium constant = K = cC + dD [products] [reactants] = [C]c [D]d [A]a [B]b K > 1 products favored K < 1 reactants favored K = 1 equilibrium A+B C + D + heat A + B + heat C+D product reactant Eq Shift reactant Eq Shift increase increase decrease decrease product increase increase decrease decrease T increase T increase T decrease T decrease Intermolecular Forces London Dispersion Forces Weakest Dipole-Dipole Forces Hydrogen Bonds Ion-Dipole Forces Strongest Forces experienced by states of matter Gas < Liquids < Solids Increasing Average Kinetic Energy Physical Properties Property of s, l, g Increases Decreases Example Water has a high boiling point because it has H-bonding, dipole, and dispersion forces. It is close to heptane (C7H16), a heavier molecule that only experiences dispersion forces . The melting point of ionic solids is extremely high compared to water which experiences all other intermolecular forces, but not ion-dipole forces. (NaCl is 1074 K and water is 273 K) Boiling Point increasing total intermolecular forces decreasing total intermolecular forces Melting Point increasing total intermolecular forces decreasing total intermolecular forces Retention of V & Shape Decreasing Increasing intermolecular intermolecular forces, forces and decreasing T & and increasing kinetic P energy of particles or T & P Gases will fill the volume and shape of the container that holds them, while solids will retain their own shape and volume regardless of the container. Surface Tension with increasing intermolecular forces The molecules on the surface have less neighbors (and therefore less stabilizing intermolecular forces) and so have a higher potential energy, which the material will try to reduce with its shape (sphere): water beading. Viscosity Vapor Pressure with decreasing intermolecular forces increasing intermolecular decreasing intermolecular Not just a property of liquids, also gases and solids. Amorphous solids change shape over time because of their forces and decreasing forces and increasing viscosity. temperature temperature Decreasing intermolecular Increasing intermolecular Ether has weaker intermolecular forces than water and a higher vapor pressure, so it evaporates much faster then forces and increasing forces and decreasing water. temperature temperature Gas Behavior Non Rigid Container: Piston balloon P1V1 T1 = P2V2 P constant V increase w/ T or # of moles T2 PV = nRT Ptotal = PA + PB + PC Rigid Container: Closed Flask V constant P increase w/ T or # of moles Phase Changes SOLID fusion LIQUID freezing evaporation GAS condensation deposition sublimation endothermic System absorbs energy from surrounds in the form of heat o Requires the addition of heat exothermic System releases energy into surrounds in the form of heat or lig o Requires heat to be decreased Phase Changes gas TEMPERATURE l <--> g liquid evaporation or vaporization ΔHvap endothermic s <--> l solid fusion ΔHfus endothermic HEAT ADDED Chapter 8 & 9 Concepts Identify the solvent and solute in a solution Like dissolves like, predict which molecules will form solutions Predict the effect of temperature or pressure on a solution Perform concentration calculations & conversions Perform dilution calculations Predict relative changes in colligative properties between multiple solutions Understand osmotic pressure & how your kidney’s work. Identify an acid/base reaction, the acid, base, conjugate acid/base Caculate Ka, Kb Use Kw to determine concentration of H3O+ or OHDiscuss how water acts as both an acid and a base Perform titration calculations Communicate how a buffer prevents large pH changes 12 CH 8 Equations & Conversions Molarity = moles of solute (mol) V of solution (L) M1V1 = M2V2 CH 9 Equations & Conversions [H3O+][ A −] [HA] Ka = - Kb = Kw = [OH ][BH+] [ B] [H3O+][OH−] = 1.0 x 10−14 pH = -log[H3O+] •Acidic solution: pH < 7 [H3O+] > 1 x 10−7 •Neutral solution: pH = 7 [H3O+] = 1 x 10−7 •Basic solution: pH > 7 [H3O+] < 1 x 10−7 Solutions, Solubility, & Concentration 1. The solute is the substance present in a lesser amount. 2. The solvent is the substance present in a larger amount. Solubility is the amount of solute that dissolves in a given amount of solvent. REMEMBER: LIKE DISSOLVES LIKE. In aqueous or liquid phase solutions solubility increases with increasing temperature Gases dissolved in liquids increase solubility with decreasing temperature and increasing pressure Communicate how much of a solute is dissolved in a solvent using concentration: % w/v Dilution: Adding more solvent to the initial solution. % v/v The number of moles solute DOES NOT CHANGE. % mass / mass M1V1 = M2V2 ppm initial values final values Molarity Colligative Properties Colligative properties are properties of a solution that depend on the concentration of the solute but not its identity. One mole of any nonvolatile solute raises the boiling point of 1 kg of H2O the same amount, 0.51 oC. One mole of any nonvolatile solute lowers the freezing point of 1 kg of H2O by the same amount,1.86 oC. Reverse Osmosis Apply pressure to reverse osmosis. This is how our kidneys filter blood Acids / Bases •A Brønsted–Lowry acid is a proton (H+) donor. Strong: •A Brønsted–Lowry base is a proton (H+) acceptor. Weak: gain of H+ H A acid + A − + H B+ conjugate conjugate acid base B base loss of H+ − H O Conjugate base Kw remove H+ = H [H3O+][OH−] O H H2O as a base H2O as an acid + H add H+ H O H conjugate acid Acid / Base Equilibrium & pH H3O+(aq) + A HA(g) + H2O(l) acid dissociation constant Ka = [H3O+][ A −] [HA] pH = -log[H3O+] - = Low pH (0 ~ 7) [H3O+] high Acidic Conditions OH- (aq) + BH+ (aq) B (g) + H2O(l) Base dissociation K b constant − (aq) [OH ][BH+] [ B] High pH (7 ~ 14) [H3O+] low Basic Conditions Common Acid / Base Reactions Neutralization reaction: An acid-base reaction that produces a salt and water. H+(aq) + OH− (aq) H—OH(l) A bicarbonate base, HCO3−, reacts with one H+ to form carbonic acid, H2CO3. H+(aq) + HCO3−(aq) H2CO3(aq) H2O(l) + CO2(g) A carbonate base, CO32–, reacts with two H+ to form carbonic acid, H2CO3. 2 H+(aq) + CO32–(aq) H2CO3(aq) H2O(l) + CO2(g) Titration AH + B A- + BH+ Acid + Base Conjugate Base + Conjugate Acid mole–mole conversion factor M (mol/L) conversion factor Moles of base [1] Volume of base [2] Moles of acid [3] Volume of acid M (mol/L) conversion factor Buffers pH of buffer = -log[H3O+] where [H3 O +] = Ka x [HA] [ A −] Chapter 10 Concepts Interpret Atomic number and mass number Know radioactive particles: alpha, beta, positron, gamma Write & solve radioactive decay equations Determine the number of half lives that pass in a given amount of time. Familiar with measurements of the amount of radioactivity Familiar with measurements of radiation absorbed Understand how radioisotopes are used in medicine 22 Atomic Symbols & Nuclear Particles atomic number (Z) = alpha particle: a the number of protons or mass number (A) = the number of protons + the number of neutrons beta particle: β or mass number (A) positron: β+ or atomic number (Z) 12 6 number of protons 6 number of neutrons 12 – 6 = 6 gamma ray: 0 e −1 0 e +1 C g 4 He 2 Nuclear Equations & Half Life original nucleus radiation emitted new nucleus = 4 He 2 0 e −1 + 0 e +1 radiation emitted g The half-life (t1/2) of a radioactive isotope is the time it takes for one-half of the sample to decay. Radioactivity amount of radioactivity 1 Ci = 3.7 x 1010 Bq. radiation absorbed The rad—radiation absorbed dose The rem—radiation equivalent for man Radioisotopes can be injected or ingested to determine if an organ is functioning properly or to detect the presence of a tumor.