CH 302 1st Edition Lecture 6 Outline of Last Lecture I. Important RemindersII. Concept of SolubilityIII. Modeling Ionic ReactionsIV. Solubility Product ConstantOutline of Current Lecture I. Important RemindersII. Reaction QuotientIII. Temperature & Solubility & SupersaturatedCurrent LectureImportant Reminders:- Precipitation: Insoluble solid that forms and drops out of solution- Spectator Ions: Ions that don’t participate in the chemistry- What is soluble?o All Na+, K+, and NO3- salts are solubleo Know your solubility rules!o Typically Ksp is given for insoluble compoundsReaction Quotient, Q:- Q is the value of the ion product at any point in a process, not necessarily at the equilibrium ion concentrations- Q is useful because you can compare it to the value of K to decide if a precipitate will formo Q = K at equilibriumo Q > K precipitate will formo Q < K no precipitate will formMix 1 liter of 0.2 molar of lead salt with 1 liter of 0.2 molar of the iodine salt. What is the value of Qsp and will a precipitate form?- Qsp = [Pb2+][I-]^2- Qsp = [0.1][0.1]^2 = 1.0 x 10^-3- Since Q > K, precipitate will formTemperature and Solubility:- Temperature dependence of solubility:o Solubility increases with increasing temperature for endothermic solutions because this makes Ksp biggero Solubility decreases with increasing temperature for exothermic solutions because this makes ksp smaller- Solubility is an equilibrium
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