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Wingardic acid is a madeup monoprotic acid that has a Ka of 4.5×10-4. Consider the titration of 32.00 mL of 0.300 M wingardic acid with 0.480 M NaOH. Note that the concentrations are not the same. Make sure sig figs are correct on your answers. Don’t round until the end. Show your work on your upload for full credit. As usual, work should follow examples as in lecture, showing BRA and/or ICE tables if appropriate and any assumptions you are making. You can use a generic HA for the acid formula. A.  The half equivalence point will be at ______ mL of titrant added and have a pH of ______? vol titrant = [v1] mL pH = [ph1] B. The equivalence point will be at ______ mL of titrant added and have a pH of ______? vol titrant = [v2] mL pH = [ph2] C.  What is the pH at the point when 24.5 mL of titrant are added? pH = [ph3]               

Pteridine is a weak base with a Kb of 1.1×10-10.  A mixture of this base with its conjugate weak acid would make a buffer that would be most effective in the pH range of _________?

[ MoEDTA ] The coordination number is [CN] The metal charge is [charge] The d electron count is d[e] The likely geometry of the choices given is [geom]

Based on what we have discussed in lecture, A. Draw on your written paper the labeled condensed orbital diagram (arrows!) for the free ion 111Rg3+. Condensed = you must use the noble gas abbreviation. See the Periodic Table page. This will be graded manually on your written work. B. The number of unpaired electrons in Rg3+ is? Type your answer in the provided space.  

A weak acid HA has a Ka of 5.9×10-5. where A- is the conjugate base. The salt NaA has a fw=156.2 g/mol. A buffer is made by dissolving 38.22 g of solid NaA in 300.0 mL of 0.250 M HA solution. Assume the volume stays constant when the solid is dissolved. A. What is the pH of this buffer?  [ph] B. The pH is changed to 6.50 by adding a certain amount of [ab]. (type in the blank one of these choices: strong acid, strong base, water) C. What is the ratio of conjugate base to acid at this new pH? [ratio]  Give a decimal answer with correct sig figs. Show work on your upload that supports your answers. Partial credit is possible!  

You can use any calculator or there is a scientific calculator in the browser. Note that you cannot print out the periodic table or equation page during the exam. Make sure you have paper and pencil so you can show your work. After you finish the exam, you must upload a scan (pdf file) of your work within 15 minutes. Be ready to do this (but no phones, etc. allowed during the exam)! Many of the questions will ask you to show your work on paper to get full credit. This will also allow me to give you credit on certain problems if your answer was correct but marked wrong because you used incorrect sig figs, for example. Write your name on every page. You must label the work for each question that requires work using the question number and circle your answer. Don’t cram this into a small space – spread it out and make it easily readable for Dr Sue. On your work, don’t forget to use correct sig figs and put units on every number and each answer. There will be a penalty up to zero points for these problems if you do not upload of work that supports your answer. Some of the problems require manual grading therefore no score will be shown when you finish! I may decide to curve the results or alter question points if necessary.

Equations and Constants Unit 4

Part b. Considering your answer in the previous question, state whether a precipitate of MF2 will form or not and type your explanation answer here. No credit without a correct explanation.

Will the following mixtures produce a BUFFER solution?   50 mL of 0.2 M NH4Cl plus 10 mL of 0.2 M NaOH    

M is the made-up metal element mysterium. A lab technician adds 1.10 g of solid potassium fluoride to 1.00 L of a 0.00010 M solution of mysterium(II) nitrate, M(NO3)2. (Assume no change in volume.) Ksp = 8.6×10-8 for the slightly soluble salt mysterium(II) fluoride, MF2 . Calculate the ion product Qsp under these conditions and report the value here. You must show work supporting your answer for full credit. You’ll be asked to explain whether a precipitate of MF2 will form or not in the next question, so make sure you have the necessary data in your work before going on.