Indicators are weak acid or bases that have different colors in their acid and b
ID: 504447 • Letter: I
Question
Indicators are weak acid or bases that have different colors in their acid and base forms. Chemists make use of these noticeable color changes by using them in acid base titration expect in stoichiometric proportions. The end point of a titration is where the indicator changes color. Selecting an indicator that changes color at a point as close as possible to the equation. (a) consider the titration curve below and the provided table of indicators. Select the appropriate indicator(s) for the titration. (b) Thymol Blue might be selected as an indicator for the titration of a weak acid with a strong base, Can you estimate the pH at the equivalence point? Yes, The equivalence point should be somewhere between a pH of 9.6 and 10.6. Yes, The equivalence point should be somewhere between a pH of 7.0 and 8.0 Yes, The equivalence point should be somewhere between a pH of 8.0 and 9.6 Yes, The equivalence point should be somewhere between a pH of 3.1 and 4.4. No, we would need to know the concentration of the titrant before we could do that. No, we would need to know the volumes of both the analyte and the titrant before we could do that.Explanation / Answer
a)
the best indicator should change its color in the equivalence point
Equivalnece point is V = 14.8 mL approx and pH of
pH = 3.8
then, choose a speices that will change color:
best option is either
bromophenol blue
methylorange
all other indicators will change before
b)
thymol blue...
the pH for this incorrect indicator will be about
pH = 8-0.6
the incorrect pH then will be between 8.0 to 9.6, choose C