CHEM1125Q 1st EditionExam # 3 Study Guide Lectures: 17 - 21Lecture 17 (April 1)Chemical EquilibriumWhat is the difference between QC and KC?QC:- QC is the reaction quotient, and can be used with any concentrations.KC:- KC is the equilibrium constant, and can only used with equilibrium concentrations.Provide the expression for the equilibrium constant for the reaction: 2H2(g) + O2(g) Û2H2O(g)- KC = [H2O]2 / [(H2)2(O2)]Lecture 18 (April 6)Gaseous EquilibriumAt 220°C, the KC for the following reaction is 4.35: N2(g) + 3H2(g) Û2NH3(g). What is the KP?- For this problem we will use the equation: KP = KC [(0.08206 L atm/mol K) x T]Δn. We are given KC and T in Celsius. The first step is to convert Celsius to Kelvin.220°C + 273.15 = 493.15K- Next we need to find the change in moles. To do this we subtract the moles of reactants from the moles of products.2 – (1+3) = -2- Now we can solve for KP.4.35 x [(0.08206 L atm/mol K) x 493.15K]-2 = 0.00266Lecture 19 (April 8)Relationship Between G and KAt equilibrium, a system has a K of 0.023 at 350 Kelvin. Find the ΔG0 of this system.- Since at equilibrium ΔG is 0, we will use the equation: ΔG0 = -RTln(K). We are given T and K, and we know that R is 8.314J/mol K. However, ΔG0 since is measured in kJ, we will first need to convert R to kJ.(8.314J/mol K) x (1kJ/1000J) = 0.008314kJ- Now all we have to do is solve-(0.008314kJ x 350K x ln(0.023)) = 10.98kJLecture 20 (April 13)Le Chatelier’s PrincipleIf 40g of H2 gas is added to the following reaction: H2(g) + I2(g) Û 2HI(aq) which direction will it shift?- In this reaction, H2 is a reactant. Remember that adding a reactant shifts the system to the right while removing a reactant shifts it to the left. Since H2 is being added here, the reaction will shift to the right.Lecture 21 (April 15)Changes in Volume and TemperatureDescribe what happens to a reaction when there is a) a change in volume, b) a change in temperature, and c) a change in concentration.a) Volume- A change in volume in a reaction does not change the value of its equilibrium constant.b) Temperature- Changes in temperature can alter a reaction’s equilibrium constant.c) Concentration- A change in concentration, like volume, does not affect a reaction’s equilibrium
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