Name: Lab Partners: Experiment Date: 02/09/2013 Due Date: 02/23/2013 Lab Exercise No. 2 Determination of Kc Values Using UV Absorption Objectives * To determine the equilibrium constant for a given reaction * To understand the concept of Le Chatelier’s Principle * To gain experience in the use of a UV Spectrophotometer Background/Concepts * A chemical equilibrium is the state reached by a reaction mixture when the forward reaction and the reverse reaction
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Sciences Experiences and outcomes The sciences framework provides a range of different contexts for learning which draw on important aspects of everyday life and work. Learning in the sciences will enable me to: • • • • • • • • • • • • develop curiosity and understanding of the environment and my place in the living‚ material and physical world demonstrate a secure knowledge and understanding of the big ideas and concepts of the sciences develop skills for learning‚ life and work develop the skills
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that works as an internal body clock to regulate biological rhythms of the sleep-waking cycle is the suprachiasmatic nucleus (SCN‚ a small group of cells in the hypothalamus). The SCN has a direct pathway to the retina of the eye‚ in which light enters. Light is an exogenous zeitgeber which also has an influence on the rhythm due to being synchronised with the SCN. The SCN is also connected to the pineal gland by a neural pathway; the pineal gland is where the hormone melatonin is manufactured. Melatonin
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applicable to the ‘real world’. The experimental also touches on the controversial area of using animals to experiment on. It seems that Stephan and Zucker’s study used highly unethical procedures‚ with only 11 out of 25 rats surviving the damage of the SCN. It therefore becomes an issue where society has to decide if sacrificing animals in scientific studies is justified by the value to society of the findings. It seems that given the extreme severity of the procedures (damaging other parts of the hypothalamus
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Stephany Matos Chem Lab: Chemical Equilibrium Lab 52 Synopsis Iron (III) ions react with thiocyanate ions (SCN-) to form iron (III) thiocyanate‚ FeSCN2+. It is represented in the equation below: Fe3+ (aq) + SCN- (aq) FeSCN2+ (aq) Therefor the equilibrium constant for this reaction is: KC = [FeSCN2+]/([Fe3+]•[SCN-] For this experiment we were able to determine the equilibrium constant KC for this reaction. First we prepared five different mixtures with known initial concentrations of
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ABSTRACT The experiment aimed to determine the equilibrium constant Keq of the formation of Fe(SCN)2+ from Fe3+ and SCN- in the equation Fe3+(aq) + SCN-(aq) ⇌ Fe(SCN)2+(aq)‚ through spectrophotometric analysis. Acidified solutions (using 0.1 M HCl) of FeCl3 and KSCN were prepared for the calibration of the UV-Vis spectrophotometer (using standard solutions) and the determination of Keq of the Fe(SCN)2+ formation (solutions with unknown concentrations). Absorbance readings of the standard and unknown
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existence of equilibrium constant‚ Kc. This constant is temperature dependent‚ and it must be calculated at given temperature. This equilibrium constant is used to improve the productivity of industrial products. Therefore‚ in our experiment Fe3+ ions and SCN- ions used to calculate the equilibrium constant Kc of formation of FeSCN2+ solution. FeSCN2+(complex ions) solution was able to absorb light due to the properties of complex ions‚ and that property helped us to determine the absorbance of different
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using a serological pipet‚ mixing them thoroughly. For Part A: Absorbance of {Fe(SCN)}2+ “Knowns” Table 1: Solution Mixtures to determine Absorbance of {Fe(SCN)}2+ “Knowns.” Test Tube | Diluted Fe3+ (mL) | Stock 0.50 M KSCN (mL) | Stock of 0.1 M HNO3 (mL) | 1 | 1.0 | 5.0 | 4.0 | 2 | 2.0 | 5.0 | 3.0 | 3 | 3.0 | 5.0 | 2.0 | 4 | 4.0 | 5.0 | 1.0 | 5 | 5.0 | 5.0 | 0.0 | For Part B: Absorbance of {Fe(SCN)}2+ “Unknowns” Test Tube | Stock 0.0025 M Fe(NO3)3 (mL) | Stock of 0.0025 M KSCN
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thiocyanate‚ KSCN. They react to produce the blood-red complex [Fe(SCN)]2+. Fe3+ + SCN- ( [Fe(SCN)]2+ The equilibrium constant expression may be expressed as: K = [pic] You will prepare a series of standard solutions that contain known concentrations of [Fe(SCN)]2+ and will determine their absorbances at 447 nanometers. The concentrations and absorbance values will be used to construct a calibration graph for [Fe(SCN)]2+. In the second part of the experiment‚ various combinations
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In this experiment‚ equilibrium will be examines in the reaction beteween the iron (III) ion and the thiocyanate ion: Fe3+ (aq) + SCN- (aq) ------ FeSCN2+ (aq) The FeSCN2+ complex ion has a blood red color while the iron and the thiocyanate ion are colorless. Therefore‚ the shift in the reaction can followed by noting a change in the intensity of the clood red color‚ which indicates a change in the concentration of the complex ion FeSCN2+. If the reaction shifts to the right‚ the blood red color
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