Research: Factors Affecting the Equilibrium Reaction of Iron

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Factors Affecting the Equilibrium Reaction of Iron (III) and Thiocyanate ions. (Revise) Research Question How does the change in temperature of Iron (III) Thiocyanatoiron, containing iron (III) ions Fe3+ (aq) and thiocyanate ions SCN¬¬- (aq), affect the absorbance of the solution? - Temperature at 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, and 60 °C (equilibrate the Iron (III) Thiocyanatoiron (aq) in various temperatures using a digital water bath, and temperature checked using a digital thermometer connected to a data logger) - Production rate of thiocynate ion measured by the degree of change in color using a colorimeter after 600 seconds since the reactants are mixed. - The quantitative data of the absorbance of the solution will allow the determination of the concentration of the Iron (III) Thiocyanatoiron using the Beer–Lambert Law. The difference in concentration of the solution per temperature point provides the precise effect of temperature on the reaction’s equilibrium position. Introduction This experiment investigates how changing a factor that affects the equilibrium reaction, in this case temperature, affects the equilibrium position. Fe 3+ (aq) + S︎CN – (aq) ⇌ Fe ( SCN ) 2+ (aq) ( ∆H = - ve ) Pale Yellow Colorless Blood Red This experiment uses Iron (III) ion and thiocyanate ion; the two chemicals are yellow colored and colorless, respectively. The product of the forward reaction is Iron (III) Thiocyanatoiron, which has a blood red color. Dynamic equilibrium is when the macroscopic properties of the reaction are in constant at a specific temperature when the rate of the forward reaction is equal to that of the reverse reaction in a closed syste... ... middle of paper ... ... percentage of light penetrated through the solution to the other side, recorded by the detector, comparing to the intensity originally illuminated. By determining the light absorption of the solution at different temperatures, different absorbance levels of each color can be quantify, thus able to determine the concentration of Iron (III) Thiocyanatoiron at equilibrium of a specific temperature in the reversible reaction. According to Frostburg State University (2010), if Red color is observed, it means that the color BlueGreen is absorbed. To determine the concentration of Iron (III) Thiocyanatoiron in the reversible reaction at different temperatures, the spectrophotometer will be set to produce BlueGreen light, which has a wavelength of 470 nm. This allows the spectrophotometer to obtain the maximum absorbance level of the solution at each temperature.

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