Chem 211 1st Edition Lecture 16 Outline of Last Lecture I. The Reaction Quotient QII. Forms of K and Q and Heterogeneous EquilibriumIII. Kc and KpIV. Determining the Direction of ReactionV. Solving Equilibrium ProblemsVI. The Simplifying AssumptionOutline of Current Lecture I. Sample Problem 17.9II. Steps in solving equilibrium problemsCurrent LectureI. Sample Problem 17.9A. PROBLEM: Phosgene is a potent chemical warfare agent that is now outlawed by international agreement. It decomposes by the reaction COCl2(g) CO(g) + Cl2(g); Kc = 8.3x10-4 at 360°C. Calculate [CO], [Cl2], and [COCl2] when the following amounts ofphosgene decompose and reach equilibrium in a 10.0-L flask.a) (a) 5.00 mol COCl2 (b) 0.100 mol COCl2B. PLAN: We know from the balanced equation that when x mol of COCl2 decomposes, x mol of CO and x mol of Cl2 form. We calculate initial concentrations, define x, set up a reaction table, and substitute the values into the expression for Qc. Since Kc is very small, we can assume that x is negligible, which simplifies the expression. We must check this assumption when we have solved for x.C. SOLUTION: a) a= 0.500 mol/ 10.0 L = 0.500 Mb) Let x = amount of COCl2 that reacts: These 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.c) Since Kc is very small, the reaction does not proceed very far to the right, so let's assume that x can be neglected when we calculate [COCl2]eqm:d) Check that the assumption is justified:e) b= 0.100 mol/ 10.0 L = 0.0100 Mf) 29% is > 5%, so assumption is not justified.g) Quadratic Equation: ax2 + bx + c = 0 h) Rearrange for quadratic i) Example: II. Steps in solving equilibrium problemsA. PRELIMINARY SETTING UPa) Write the balanced equation.b) Write the reaction quotient, Q.c) Convert all amounts into the correct units (M or atm).B. WORKING ON THE REACTION TABLEa) When reaction direction is not known, compare Q with K.b) Construct a reaction table.c) Check the sign of x, the change in the concentration (or pressure).C. SOLVING FOR x AND EQUILIBRIUM QUANTITIESa) Substitute the quantities into Q.b) To simplify the math, assume that x is negligible: c) ([A]init – x = [A]eq ≈ [A]init)d) Solve for x.e) Check that assumption is justified (<5% error). If not, solve quadratic equation for x.f) Find the equilibrium quantities.g) Check to see that calculated values give the known K.= 2.5 x 10-3 =