Lab Report Pka of Methyl Red

Determination of the pKa of Methyl Red by UV-Vis Spectroscopy February 16, 2010 (Partner:) plagiarise The purpose of this experiment was to withstand the pKa for an loony toons-base indicator. A spectrometer was used to take care the pKa of methyl radical radical carmine. The standardization curves were created by analyzing samples of known concentration at pHs hearty above and below the pH indicator roll for methyl red. Then samples of known pH were analyzed. By, solving the formation of comparabilitys victimisation linear algebra, the concentrations of the indicator and the coupled base were make upd. The Henderson-Hasselbach equation predicted that the pH for these solution plotted against the pound of the ratio of the twain species would give back a line whose Y-intercept equaled the pKa for methyl red. The value obtained was 4.96(1), which has a percentage error of 1.9. Perhaps, if this were corrected for temperature there would be blush greater agr eement with the accepted value. INTRODUCTION The purpose of this experiment was to determine the pKa of an acid-base indicator (methyl red). All indicators are weak acids, and as such(prenominal) move over a dissociation invariant, or Ka. The subscript a signifies that the constant is for an acid. The lower case p indicates that the value is the detrimental record (base 10) of the constant.

The Ka expression, Ka=H+In-HIn[1] (1) is the equilibrium for the dissociation of the weak acid, where HIn is the acid and In- is the conjugate base. This is represented by the chemical equation: HIn ?H++ In- [1]Fi gure 1: Chemical equation for the dissociati! on of an acid-base indicator. Methyl red is a monoprotic organic acid. Figure 2 is a structural feigning of methyl red. Figure 2: Chemical twist of methyl red By plotting the data as the pH versus the log term of the Henderson-Hasselbach Equation, pH=pKa+logIn-HIn[2](2) the pKa was determined. The plot was linear with the Y-intercept equaling the value for the pKa. The pH was determined...If you want to get a full essay, order it on our website: OrderCustomPaper.com

If you want to get a full essay, visit our page: write my paper