CHEM 101 1st EditionExam # 2 Study Guide Lectures: 7 – 12General Properties of Aqueous Solutions- When an ionic compound dissolves in water it dissociates into its component ions. The dissolved ions are surrounded by H2O molecules o Example: NaCl (s)  Na+ (aq) + Cl – (aq)- Not all ionic compounds are dissolvable in watero When an ionic compound containing a polyatomic ion is dissolved in water atomsin the polyatomic ion stay togethero Pb (NO3)2 (s)  Pb (aq) + 2 NO3 (aq)- When a molecular compound dissolves in water the molecules remain intact and are evenly dispersed throughout the water o CH3OH (l)  CH3OH (aq) - Some molecular compounds (weak acids) will partially dissociate when dissolved in watero HF (g) ↔ H (aq) + F (aq) Half arrows in both directions mean the reaction goes in both directions- Precipitation Reaction – an exchange reaction in which an insoluble compound is formedExample: AgNO3 (aq) + NaCl (aq)  AgCl (s) + NaNO3 (aq)Note that the solubility chart will be given to you at the examLecture 8- Strong Acids – dissociate completely when dissolved in water into H+ and anionso Example: HCl (g)  H+ (aq) + Cl- (aq)o 7 strong acids Hydrochloric acid – HCl Hydrobromic acid – HBr Hydroiodic acid – HIThese 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. Chloric acid – HClO3 Perchloric acid – HClO4 Nitric acid – HNO3 Sulfuric acid – H2SO4- Strong Bases – fully dissociate into cations and OH- o Example: KOH (s)  K+ (aq) + OH- (aq)o Any soluble metal hydroxide is a strong base o Alkali metal hydroxides LiOH, NaOH, KOH, RbOH, CsOHo Heavy alkaline earth metal hydroxides  Ca(OH)2, Sr(OH)2, Ba(OH)2Note: the strong acids and bases will NOT be given to you, so you need to memorize them!Also the first two columns of the periodic table, besides Be and Mg, are strong bases when paired with OHAlso note that the polyatomic ions and their charges are still relevant, so make sure you still remember them from the last testLecture 9Identifying Electrolytes - use strong and weak acids and bases to predict strong and weak electrolytes - Ionic Compounds o Strong electrolytes – strong baseso Weak electrolytes – noneo Non-electrolytes – none- Molecular Compounds o Strong electrolytes – all strong acidso Weak electrolytes – weak acids and weak bases o Non-electrolytes – all others- pH is a negative log scale of H+ concentrationo pH = -logH+ o H+ = 10-pH M- pOH o pOH = -logOH- o OH- = 10-pOH- pH + pOH = 14Note: The formula for molarity and dilution equations will be given to you, make sure you know how to do the problems though!Lecture 10Units of Energy - 1 joule = 1 kg x m2/s2- Calorie – amount of energy required to raise the temperature of 1 gram of H2O from 14.5 degrees Celsius to 15.5 degrees CelsiusChange of Internal Energy of a System∆E = Efinal – Einitial o Energy going out of a system ∆E is negativeo Energy going into a system ∆E is positive Heat – changes in the internal energy of a system occur in the form of both heat being lost or gained by the system and work being done on or by the system∆E = q + w- Q is heat and w represents work- Heat absorbed from surroundings by the system q is positive - Heat released from the system to the surroundings q is negativeNote: the formula for kinetic energy will be given to youLecture 11- The change in enthalpy equals the heat gained or lost for a reaction or process at constant pressureo ∆H = q- Exothermic – process that results in the loss of heat from te system to its surroundingso q < 0o ∆H < 0- Endothermic – process that results in the system gaining heat from its surroundings o q > 0o ∆H > 0- Enthalpies of Reactionso ∆Hrxn = Hproducts - HreactantsLecture 12Calorimetry- The measurement of heat flow during physical and chemical changes - Calorimeter – device for measuring heat flow - Amount of heat lost from the system is equal to the heat absorbed by the surroundings qsystem = -qsurroundings- Final temperature of the system and surroundings will equal each otherDetermining Changes in Enthalpy using Calorimetry - The system in calorimetry may also be a chemical reaction (rxn). The solution is considered the surroundings.qsystem = qsurroundings qrxn = -Csoln x msoln x