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Indicators

Posted: Thu Dec 01, 2016 11:59 pm
by Nilla Sivakumar 2H
Will there be questions on indicators on the final?

Re: Indicators

Posted: Fri Dec 02, 2016 10:09 am
by Megan Yabumoto 3K
The other day in class Dr. Lavelle mentioned that the big idea of indicators is that the best indicators to use are the ones that have an end point that equals the stoichiometric point of a titration. There is a HW problem in chapter 13 that has us find the range for pH of indicators for a given pH. In that case, it is just +/- 1 of the pH. I do not know whether there will be a problem like this on the final, but as long as you understand this main concept you should be able to answer any questions about indicators.

Re: Indicators

Posted: Fri Dec 02, 2016 10:22 am
by Sophia Eliopulos 2I
It is probably a good idea to remember that indicators are weak acids that give a strong color change with pH. The popular indicator phenolphthalein in acid appears colorless, however in base appears pink. The H+ release results in a structural change so light is absorbed differently. The color change for this example occurs when pH=pKIn. A good indicator has an end point = stoichiometric point. Hope this helps.

Re: Indicators

Posted: Fri Dec 02, 2016 7:00 pm
by Malavika_Theophil_3H
During the review session today, he went over them, so it might be useful to know them.