The Cr 2 O 7 2- in the above solutions (photos), used in Experiments 1 and 2, wa

Question

The Cr2O72- in the above solutions (photos), used in Experiments 1 and 2, was atually excess Cr2O72- from a redox reaction with butanol (C4H9OH) performed by refulxing in acid; this redox reaction produced butanoic acid (C4H7O2H) and Cr3+

A) write and balance the redox reaction peformed (show steps)

B) A standard solution of 0.3000M Na2Cr2O7 was used to as a reactant to generate the solutions containing the excess C2O72- (these solutions were the ones tirated in Part A), on average, how many moles of Cr2O72- reacted with butanol for Experiments 1 and 2?

ou dissolve 5.0235g of Fe(NH)(SO2 6H20 and quantitatively volumetric flask (+ 0.15mL tol certain volume of it into a 50mL buret. You also transfer 25mL of a solution contai CrO into a 250mL Erlenm drops of diphenylaminesu with the Fe(NH) (SO4) 610 solution you made. The following reaction takes place in the Erlenmeyer flask during the titration: and quantitatively transfer it into a 250mL rance). You dilute this solution to the calibration mark and pour a lution containing excess eyer flask using a 25mL pipet (tolerance +/- 0.02) and introduce 5 nronate indicator to the solution. You proceed to titrate the excess Cn072. rlenm A) The tables below include data collected from 2 separate experiments o formed, Experiment Fill in the table for A) The tables below include data collected from 2 separate experiments you per and Experiment 2, using 2 different solutions containing excess CrO taining excess Cr207 Fill in the table for each trial. EXPERIMENT I 25 37.06 10.45 25 35.14 8.32 TRIALS 25 35.82 9.31 4 25 36.48 25 36.90 10.21 buret reading, final (mL) 9.45 buret reading, initial (mL) Endpoint volume (mL) of Fe(NH4) (SO4)2 moles of excess CrO present Three (3) trials used to calculate average (Mark with "X") .73 Average moles of excess Cr,O Standard deviation B) Show one (1) of your calculations from Experiment I to determine the moles of Cr20 present 5,02359 FeQwHuta(w) 2.GHaoCL mo l Ftataa 39a 148 8 mol CraO mol Fea Titration Workshop CHEM120 -Johnson

Explanation / Answer

A) Balanced reaction:-

3C4H9OH + 2Cr2O72- + 16H+ ------> 3C3H7COOH + 4Cr3+ + 11H2O

B) Moles of Cr2O72- reacted = molarity*volume of solution

C) Moles of butanol reacted = (2/3)*moles of Cr2O72- reacted

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