AS.030.205 Midterm: Exam 2 Solutions Fall 2013(1)

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turquoisegnu128

14 Mar 2019

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Exam ii chem 205 october 24, 2013 key. I agree to complete this exam without unauthorized assistance from any person, materials, or device. 100: no electronic devices of any kind, such as calculators, cell phones, or advanced digital watches are allowed. Answers that are not written in the boxes will not be considered for grading: be neat and clear. Make sure we know which answer is to be graded: some questions will have points deducted for incorrect responses. Longer synthetic routes receive fewer points than shorter, more direct answers: keep your answers brief. The stereochemistry in structural drawings and reaction schemes is not shown unless explicitly indicated with wedge-bond designations. Abbreviations used: me = methyl, et = ethyl, pr = propyl, bu = butyl, pe = pentyl, ph = phenyl, (i. e. , benzene as a substituent), aco = acetate (h3ccoo). 1 (28 pts) provide the missing starting material, major organic product(s), conditions, or reagent(s) for the following transformations.

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Mass of beaker: 59

Mass of beaker and citric acid: 61

Mass of beaker and citric acid (after cooling): 61.06 or 61.1

Volume of NaOH: 15mL

Syringe Reading, mL	Citric acid added, mL	pH
30	2	11.20
28	3	10.81
27	4	10.21
26	5	10.
25	6	9.58
24	7	8.35
22	9	7.02
20	11	6.72
19	12	6.68
18	13	6.39
17	14	6.12
16	15	5.77
15	16	5.72
14	17	5.66
13	18	5.22

Syringe Reading, mL	Citric acid added, mL	pH
30	1	11.24
29	2	10.78
28	3	10.48
27	4	10.12
26	5	9.92
25	6	9.82
24	7	7.96
23	8	7.46
21	10	6.83
19	11	6.75
18	12	6.65
17	13	6.21
16	14	5.82
15	15	5.63
14	16	5.42

Mass of citric acid: 2g

Moles of citric acid: 0.0104

(MW = 192.0 g/mol)

Molarity of citric acid: 0.104M

(volume of solution = 100 mL)

Trial 1 equivalence point: 10+7=17/2= 8.5

Trial 2 equivalence point:10+7=17/2=8.5

Molarity (Trial 1):

Molarity (Trial 2):

Average Molarity:

I need help calculating the molarity of the citric acid per trial, please help and show work.

PreLab Experiment #3: Cyclic Voltammetry

Please complete these set of questions before coming to the lab to perform Experiment #3.

Name:__________________________________ Date:_______________ Score:__________

(2pts) What is cyclic voltammetry.

(2pt) Which of the following is a stronger electrolyte KCl or KNO₃?

(10 pts) Provide the weight of volume missing in the Table below in preparation for the experiment

#	Reagent	Volume	Molarity	Weight or Volume	Solvent
1	K₃Fe(CN)₆	100 mL	50mM		1mM KNO₃
2	KNO₃	500 mL	0.1 M		H₂O
3	KCl	500 mL	0.1 M		H₂O
4	K₃Fe(CN)₆	50 mL	2 mM		0.1 M KNO₃
5	K₃Fe(CN)₆	50 mL	4 mM		0.1 M KNO₃
6	K₃Fe(CN)₆	50 mL	6 mM		0.1 M KNO₃
7	K₃Fe(CN)₆	50 mL	8 mM		0.1 M KNO₃
8	K₃Fe(CN)₆	50 mL	10 mM		0.1 M KNO₃
9	K₃Fe(CN)₆	50 mL	2 mM		0.1 M KCl
10	K₃Fe(CN)₆	50 mL	4 mM		0.1 M KCl
11	K₃Fe(CN)₆	50 mL	6 mM		0.1 M KCl
12	K₃Fe(CN)₆	50 mL	8 mM		0.1 M KCl
13	K₃Fe(CN)₆	50 mL	10 mM		0.1 M KCl

(6 pts) List the specific data you need to record on your lab notebook for Experiment#3.

You can create a table and/or sample graph indicating what data you need to fill in.

Table #1: Volumes

Trial	Deionized Water (mL)	1.0 M KI (mL)	H₂O₂ (mL)	Temperature of Tap Water (â¦C)
1	100	50	50	18.7
2	125	25	50	19.3
3	125	50	50	19.5
4	100	50	50	50.0

Table #2: Trial #1 data

Time (min)	Volume (mL)	Time (min)	Volume (mL)
3	0	8	12
4	1	9	15
5	4	10	18
6	6	11	25
7	8	12	27

Table #3: Trial #2 data

Time (min)	Volume (mL)	Time (min)	Volume (mL)
6.27	0	11.27	6
7.27	1	12.27	7
8.27	3	13.27	9
9.27	4	14.27	11
10.27	6	15.27	12

Table #4: Trial #3 data

Time (min)	Volume (mL)	Time (min)	Volume (mL)
5.37	0	9.37	5
6.37	2	10.37	6
7.37	3	11.37	8
8.37	4	12.37	9

Table #5: Trial #4 data

Time (min)	Volume (mL)	Time (min)	Volume (mL)
1.30	0	6.30	62
2.30	5	7.30	82
3.30	13	8.30	100
4.30	26	9.30	115
5.30	41	10.30	132

Table #6: Results

Trial	Temperature (K)	3% H₂O₂ (M)	KI (M)	Rate (L/min)
1	291.85	0.176	0.005	0.00225
2	292.45	0.176	0.0025	0.00075
3	292.65	0.176	0.005	0.0009
4	323.15	0.176	0.005	0.0132

Above are 6 tables of data from an experiment I performed. My goal is to determine the reaction order with respect to H2O2 and I- , the rate law for the reaction, and the activation energy for the reaction. My first issue is table #6. I do not believe that I have figured the correct (M) for the H2O2 and KI or the correct rate. I am supposed to make sure to express the concentrations based on the values after dilution due to mixing. I am not sure how to correctly calculate that.

AS.030.205 Midterm: Exam 2 Solutions Fall 2013(1)

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