Ty’Airea Blash6-7: Ionization Constants of Weak AcidsAn acid-base indicator is usually a weak acid with a characteristic color in the protonated anddeprotonated forms. In this assignment, you will monitor the color of an acetic acid solution containingBromocresol Greenas an indicator, as the pH is changed and then you will estimate the ionizationconstant,Ka, for the indicator.1.StartVirtual ChemLab,selectAcid-Base Chemistry,and then selectIonization Constants of WeakAcidsfrom the list of assignments. The lab will open in the Titrations laboratory. Bottles of 0.1104 MNaOH and 0.1031 M HAc (acetic acid) will be on the lab bench. The buret will be filled with theNaOH solution and a beaker containing 10.00 mL of the HAc solution will be on the stir plate. Thestir plate will be on, a small amount ofBromocresol Greenindicator will have been added to thebeaker, and a calibrated pH probe will also be in the beaker so the pH of the solution can bemonitored.2.What is the color and pH of the solution?pH = 2.87 and Color is Yellow3.On the buret, the horizontal position of the orange handle is off for the stopcock. Open the stopcockby pulling down on the orange handle. The vertical position delivers solution the fastest with threeintermediate rates in between (slow drop-wise, fast drop-wise, and slow stream). Turn the stopcock tothe second position or fast drop-wise addition. Observe the color of the solution and close thestopcock when the color turns clear by double clicking on the center of the stopcock.
