CHEM 2PC3 Lecture Notes - Lecture 2: Thermodynamic Equilibrium, Rate Equation, Reaction Rate Constant

67 16 Determination of a Keq Practice Questions 1 A 0.9% (w/w)aque solution? What is the molality of the solution in #1? Which of the following concentration units is not sensitive to temperature: and/or percent by mass? From the tabl (include the proper units on k): ous NaCI solution has a density of 1.0 g/ml. What is the molarity of this 2, 3. molarity, molality, 4. e of information below determine the rate law for A and B in the generic reaction Initial [AI (M) Initial [B] (M) Rate (M/s) 0.25 0.50 0.25 0.40 0.40 1.20 1.32x10-2 2.55x10-2 0.120 as written? Explain. Introduction and Objectives The equilibrium constant is a thermodynamic quantity that allows the determination of the extent of a chemical reaction. Using the equilibrium constant it is possible to calculate the concentrations of reactants and products present at equilibrium for a particular chemical reaction at a particular temper reaction of interest here is: ature. The The product (a complex ion) formed in this reaction is intensely colored red. Its concentration will be rotions uill he determined using simple

For the generic single-step reaction, below, draw an Arrhenius plot (In(k) vs 1/T). Is the reaction faster at high temperatures or low temperatures? A + B rightarrow^k AB Now consider the reaction B + C + D rightarrow E which is comprised of the two steps shown below where all reactions are first order for all species. The first step is a rapid equilibrium between B, C, and BC, with equilibrium constant K=[BC]/([B][C]). B + C BC BC + D rightarrow E Show that the dependence of the overall reaction rate on temperature is given by the equation below, where Delta H degree is the enthalpy change for the first step and E_a is the activation barrier for the second step k = A exp[-(E_a + Delta H^-degree)/RT]