Exp8LabRep.pdf - Experiment 8 The Effect of Temperature on an Equilibrium Constant Pre-laboratory Questions Name Hyo Sun Kim Lab Section CHEM152 D2 Date

Exp8LabRep.pdf - Experiment 8 The Effect of Temperature on...

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1 Experiment 8 The Effect of Temperature on an Equilibrium Constant Pre-laboratory Questions Name: Hyo Sun Kim Lab Section: CHEM152 D2 Date: 4/25/20 1. Consider the reaction below. Co(H 2 O) 6 2+ (aq) + 4 Cl ˉ (aq) CoCl 4 2 ˉ (aq) + 6 H 2 O (l) The equilibrium constant expression (K c ) of the reaction does not include the concentration of H 2 O even though the reaction produces six moles of water. Explain. : Pure solid and liquid aren’t considering an equilibrium constant. Since the H 2 O is in liquid state and concentration of pure liquid and solid are constant so there are excluded from expression of equilibrium constant. [H2O] =density of H2O/Molar mass of H2O . Concentration of H2O liquid is constant at a particular condition. Since density is constant at particular temp and pressure condition. Molar mass also solid. 2. In the following reaction, NO 2 is a brown gas and N 2 O 4 is colorless. NO 2 (g) 2 N 2 O 4 (g) (brown) (colorless) a. When the temperature decreases, the color of the equilibrium mixture gets lighter. Is this reaction exothermic or endothermic? : This reaction is an exothermic reaction. When temperature increased the equilibrium shifts towards left generating higher concentration of NO2.(equilibrium shifted to NO2). b. What will happen to the value of the equilibrium constant, K c , if the temperature of the reaction is increased? : The equilibrium is characterized by ∆H = -57.23kJ/mol. Which is an exothermic reaction.NO2 is favored at higher temperature, while at lower temperatures dinitrogen tetroxide predominates. When the temperature is increased the equilibrium constant Kc increases. When the temperature is increased energy is added to the system in order to offset this change system Increase the concentration of NO2 and decrease the concentration of N2O4.The value of equilibrium constant depends on temperature for two reasons. There is a factor of the temperature in the relationship between the standard free energy and equilibrium constant. In addition, the standard free energy depends on temperature. At room temperature the equilibrium constant for this reaction is extremely small.
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2 3. The temperature-dependence of the equilibrium constant was observed for a particular reaction. A plot of lnK
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