## Chemical Reactions

Part A:

• Write the balanced half reaction for permanganate ion being reduced to manganese(II) ion in acidic solution.

• Write the balanced half reaction for oxalic acid being oxidized to carbon dioxide.

• Balance the overall redox reaction (equal moles of electrons for both half-reactions).

Find the mole ratio between titrant and analyte.

• Part A: Correct the titration volumes during standardization with the volume for the blank titration.

• Do at least 1 example of the calculation of the molarity of KMnO4 titrant (mass of sodium oxalate to moles of oxalate, then to moles of KMnO4, and lastly to molarity of permanganate).

• Do the statistics for the good trials and find the 90% confidence interval, quoting the t- value used.

• Find the absolute uncertainty of mass of primary standard. Find the relative uncertainty in the mass for a chosen trial.

• Find the absolute uncertainty for the uncorrected titration volume. Find the absolute uncertainty for the corrected titration volume.

• Find the relative uncertainty in the corrected titration volume using the chosen trial.

• Propagate the relative uncertainties in mass and in corrected titrant volume to find the relative and absolute uncertainties in the KMnO4 molarity.

Part B:

• Correct the titration volumes using the blank for the analysis of unknown U2.

• Do at least 1 example of finding the % sodium oxalate in the unknown U2 (concentration and volume of KMnO4 to moles of KMnO4, then to moles of oxalate, then to mass sodium oxalate, and lastly to mass % in sample solid).

• Do the statistics for the good trials and find the 90% confidence interval, quoting the t- value used.

• Quote the relative uncertainty in your KMnO4 molarity from Part A.

• Find the relative uncertainty in the mass of unknown, based on a chosen typical trial.

• Find the relative uncertainty in the corrected titrant volume, using your chosen trial.

• Propagate the three relative uncertainties to find the absolute uncertainty in the % sodium oxalate.

• Summarize the main data and results in tables, giving absolute uncertainties with each value and result. Give the statistical values at the bottom of the table.

• List possible error sources.

Report 4 (R4)

Please see the general requirements in the syllabus. Given below are some tips you may find helpful.

Data Tables and Equations:

• Most of the data can be presented in two tables, with statistical results at the bottom of each.

• Include the blank titration as the first “trial”. Include a row for uncorrected titrant volumes as well as blank-corrected titrant volumes.

• In the second table, include a row for the mass of pure Na2C2O4 found in the unknown.

• Use absolute tolerance values (±uncertainty) with quantities except for intermediates like moles and mass of sodium oxalate in unknown. Have the tolerance either in the cells or in the row headings.

• Don’t forget the units in row headings.

• Write the two half-reactions in the titration, and the balanced overall redox reaction.

Include the states of matter with chemical equations.

• Give general formulas for finding molarity of KMnO4 and for finding %Na2C2O4.

These can be done in one-step or multiple steps.

Results and Discussion:

• Is the titrant concentration close to the target? How precisely known is the titrant molarity?

• What likely errors (random and systematic) can affect the results of standardization?

Think about the equipment and procedure used.

• What actual errors occurred (eg. bad trials).

• How does the error affect the molarity (high or low)?

• Is the % composition of the unknown sensible? How precise are the results?

• What additional errors can affect the unknown analysis?

• Comment on the chemistry in this analysis. Suggest possible applications of the method (research in textbooks, journals or the internet).

• Any suggestion on how to improve on the method or alternative methods for finding

%oxalate?

• Don’t forget a concluding paragraph with the main results and overall comments about

the analysis.

Unknown Analysis 2 (U2)

For this unknown analysis, you must fill out the cover sheet with the unknown sample number, and the % by mass of sodium oxalate as a 90% confidence interval.

Comments from Support Team: I want you to do all the calculation for part A and B. See the home page for the detailed.

I want you to write like the example. Especially for the discussion part and please write details for errors part ( see the example)

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