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CHM120H5 Lecture Notes - Lecture 1: Phenanthroline, Reaction Rate Constant, Activation Energy

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14 Apr 2016

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In part a, the rate constant at a particular temperature is determined. Part b is the determination of the activation energy. The bidentate ligand 1,10-phenanthroline (phen), like pyridine and ammonia, is a base and in acid solution it is protonated. The tris-(1,10-phenanthroline_ iron(ii) cation is very stable for the reaction: Fe(h2o)6 + + 3phen fe(phen)3 + + 6h2o. If acid is added to a neutral solution of the ferrous complex, the equilibrium will be disturbed. Therefore, if there is an excess of acid present all of the 1,10- phenanthroline is protonated as the complex dissociates, with an overall reaction: Fe(phen)3 + + 3h+ + 6h2o fe(h2o) 6 + + 3 phen h+ This first order reaction and its rate is what was investigated in this experiment. The data collected in part a and part b was then used to find the activation energy of the reaction.

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Related Questions

1) Assuming that all of the 1,10, phenanthroline is consumed in the formation of "tris" complex, what is the initial concentration of the complex ion solution in the flask?

My teacher worked this one in class for us: Fe(phen)2+/3, 0.001M phen,100ml volume flask

0.015L phen*0.001 mol phen/ 1L = 0.000015 mol phen *1 mol tris/ 3 moles phen = 0.000005 moles tris/0.100L= 5*10^-5 M tris

2) Using the value obtained in this experiment, and the initial concentration of the complex ion, calculate the rate of the hydrolysis reaction in this experiment.

3) How long does it take in minutes to reduce the concentration of tris( 1,10 phenanthroline) iron (II) complex ion to 10% of its initial value?

I jus need a step by step solution for 2 and 3. Please help!

Please answer the question neatly and clearly.

Be as detailed as possible. Show examples if necessary. Thanks*

Lab B4 Le ChÃ¢telier's Principle Introduction All chemical reactions proceed until equilibrium is reached, provided none of the reactants or the products are removed from the reaction mixture. Le ChÃ¢telier's principle describes what happens to an equilibrium after it has been disturbed (Ebbing/Gammon, Sections 14.7, 14.8, and 14.9). 05 Purpose You will study the application of Le ChÃ¢telier's principle by seeing the effect of the addition of Fe and SCN-to an equilibrium mixture of Fe", SCN, and Fe(SCN)ê³¼, the effect of the addition of an acid to an equilibrium mixture of Ni2, NHs, and Ni(NH)% the effect of the addition of an acid and a base on the equilibrium involving an indicator; the effect of acids and bases on the solubility of Ca(OH)2 in water and the effect of temperature on an equilibrium mixture of Co', cr, and CoCla 2- New Substances In this experiment you will encounter some substances that you may not have seen before. The reaction between Fe and SCN (thiocyanate ion) gives Fe(SCN)2. This substance is a deeply colored complex ion. Other complex ions that you will encounter are Ni(NHs)6 and CoCl These substances result from the reaction between Ni? and NH3 and from the reaction between Co and CI, respectively. You will also study an equilibrium involving methyl orange, an indicator. Indicators are discussed in Appendix D. Read the second, third, and fourth paragraphs of that appendix to gain an understanding of the physical and chemical properties of this indicator. Concept of the Experiment Le ChÃ¢telier's principle can be described in the following way: "When a system in chemical equilibrium is disturbed by a change of temperature, pressure, or concentration, the system shifts in equilibrium composition in a way that tends to counteract this change of variable" (Ebbing/Gammon, Section 14.7). This statement explains the effects that you will encounter in this experiment. Procedure lib Getting Started 1. Obtain 3 small test tubes and a piece of filter paper Obtain directions for discarding the solutions that you will use in this experiment from your laboratory instructor. Be careful handling the solutions used in this experiment. 2. 3. CAUTION: Solutions of ammonia, hydrochloric acid, and sodium hydroxide can cause chemical burns, in addition to ruining your clothing. Do not use your finger as a stopper when mixing these solutions. If you spill any of these solutions on you, wash the contaminated area thoroughly and immediately report the incident to your laboratory instructor. You may require further treatment. May not be scanned, copied or duplicated, or posted to a publily accessible website, in whole or in part be o 2013 Cengage Leaming All Rights Reserved. custom page 125

Please answer the question neatly and clearly.

Be as detailed as possible. Show examples if necessary. Thanks*

Lab B4 Le ChÃ¢telier's Principle Introduction All chemical reactions proceed until equilibrium is reached, provided none of the reactants or the products are removed from the reaction mixture. Le ChÃ¢telier's principle describes what happens to an equilibrium after it has been disturbed (Ebbing/Gammon, Sections 14.7, 14.8, and 14.9). 05 Purpose You will study the application of Le ChÃ¢telier's principle by seeing the effect of the addition of Fe and SCN-to an equilibrium mixture of Fe", SCN, and Fe(SCN)ê³¼, the effect of the addition of an acid to an equilibrium mixture of Ni2, NHs, and Ni(NH)% the effect of the addition of an acid and a base on the equilibrium involving an indicator; the effect of acids and bases on the solubility of Ca(OH)2 in water and the effect of temperature on an equilibrium mixture of Co', cr, and CoCla 2- New Substances In this experiment you will encounter some substances that you may not have seen before. The reaction between Fe and SCN (thiocyanate ion) gives Fe(SCN)2. This substance is a deeply colored complex ion. Other complex ions that you will encounter are Ni(NHs)6 and CoCl These substances result from the reaction between Ni? and NH3 and from the reaction between Co and CI, respectively. You will also study an equilibrium involving methyl orange, an indicator. Indicators are discussed in Appendix D. Read the second, third, and fourth paragraphs of that appendix to gain an understanding of the physical and chemical properties of this indicator. Concept of the Experiment Le ChÃ¢telier's principle can be described in the following way: "When a system in chemical equilibrium is disturbed by a change of temperature, pressure, or concentration, the system shifts in equilibrium composition in a way that tends to counteract this change of variable" (Ebbing/Gammon, Section 14.7). This statement explains the effects that you will encounter in this experiment. Procedure lib Getting Started 1. Obtain 3 small test tubes and a piece of filter paper Obtain directions for discarding the solutions that you will use in this experiment from your laboratory instructor. Be careful handling the solutions used in this experiment. 2. 3. CAUTION: Solutions of ammonia, hydrochloric acid, and sodium hydroxide can cause chemical burns, in addition to ruining your clothing. Do not use your finger as a stopper when mixing these solutions. If you spill any of these solutions on you, wash the contaminated area thoroughly and immediately report the incident to your laboratory instructor. You may require further treatment. May not be scanned, copied or duplicated, or posted to a publily accessible website, in whole or in part be o 2013 Cengage Leaming All Rights Reserved. custom page 125