experiment 34 formal.docx - Sabrina Fregoso Professor...

This preview shows page 1 - 4 out of 10 pages.

The preview shows page 2 - 4 out of 10 pages.
Sabrina FregosoProfessor FarnumChem 112MW 7:35 am27 September 2018Experiment 34: An Equilibrium Constant
Abstract:In this experiment, the equilibrium constant of a chemical system was determined using aspectrophotometer. This process was done using a spectrophotometer connected to the PascoCapstone software to determine the absorbance and percent transmittance. First, a set of standardsolutions were prepared and calibrated through a spectrophotometer to establish a calibrationcurve from the absorbance and percent transmittance. Then that same process was followed toget the absorbance for a set of test solutions. The data collected in the first part was plotted usingMicrosoft Excel. The equilibrium constant for a soluble equilibrium was determined throughcalculations using the slope from the calibration curve. As a result, the average magnitude of anequilibrium constant, Kc, was ~ 309.36. The standard deviation of Kcwas ~55.025. The relativestandard deviation of Kcwas ~17.79%RSD.The quality of the data taken through the PascoCapstone software was executed well and the graphs that were as a result, were neat and precise.Introduction:The main objective of this experiment is to determine the equilibrium constant, Kc, of aset of test solutions. This objective will be met by conducting a series of chemical mixtures andgathering the absorbance and transmittance using a spectrophotometer connected to the PascoCapstone software. The Pasco software constantly records the absorbance and percenttransmittance simultaneously. There is a total of five test solutions that have 5 mL of 0.002 MFe(NO3)3, different volumes (mL) of 0.002 M NaSCN, and different volumes (mL) of 0.1 MHNO3. The overall reaction is expressed as:Equation 1:Fe3+(aq)+ SCN-(aq)↔ FeSCN2+(aq)It is assumed that the position of the equilibrium is driven so far to the right due to the excessFe3+, this as a result complexes all the SCN-to form FeSCN2+.Spectrophotometric methods involve the interaction of electromagnetic (EM) radiationwith matter. The most common EM spectrums used for analysis are the ultraviolet, visible, andinfrared regions. The degree of absorbed radiation or the intensity of the transmitted radiation ismeasured using a spectrophotometer, which measures transmitted light intensities withphotosensitive detector at a specific visible wavelength. The wavelength that the absorbing ionsor molecules have a maximum absorption of visible radiation is determined and set in the

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 10 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
N/A
Tags
Chemistry, Equilibrium, pH, Chemical reaction, SCN

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture