CHEM 7L Lecture Notes - Lecture 3: Desiccator, Standard Deviation, Conjugate Acid
11 Oct 2017
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If you perform multiple sets of n measurements, uncertainty decreases (standard error of the mean). As you increase the number of trials, your standard deviation approaches sigma. %rsd, what is your standard deviation relative to what you"re trying to measure. Caveat: ligand must be deprotonated to bind to al3+. Something is donating electrons and something is accepting electrons. Low ph is bad because we are creating hhq. High ph creates [al(oh)4]- which is soluble and that"s bad. At neutral ph hhq is soluble which may cause it to precipitate out of solution. The acid and the conjugate base is ch3cooh and ch3coo- So far we have allowed crucibles to cool in the desiccator and weighed them. Must cool in the desiccator (active ingredient is caso4) so we can get rid of all the water. Must dissolve again to get rid of impurities. Possible that hhq has precipitated and we don"t want that yet.
