Name
Group
Results
1. Qualitative examination of equili
ia and Le Chatelier's Principle (20 pts)
(You may scan and incorporate a pdf of your group’s data sheet.)
Well #
Contents (drops)
Observations
1
Fe(NO3)3 [3]
2
KSCN [3]
3
Fe(NO3)3 [1]/KSCN [1]
4
Fe(NO3)3 [2]/KSCN [2]
5
Fe(NO3)3 [3]/KSCN [3]
For 6-13 all wells start with: Fe(NO3)3 [3]/KSCN [3]
6
Distilled water [2] (control)
7
Fe(NO3)3 [2]
8
KSCN [2]
9
KSCN [4]
10
KSCN [1, 1M]
11
Na2HPO4 [2]
12
H2SO4 [2]
13
KSCN [1, 1M]/H2SO4 [3]
For 14-18 materials are: 0.0025M Fe(NO3)3
0.1M HNO3/1M KSCN
14
As above 1/4/4
15
As above 2/3/4
16
As above 3/2/4
17
As above 4/1/4
18
As above 5/0/4
1.
2. Beer's Law Plot for the Abso
ance of Fe(SCN XXXXXXXXXXpts)
(You may scan and incorporate a pdf of your group’s data sheet or include a pdf of your group’s Excel page.)
Test Tube #
[Fe3+]initial=[Fe(SCN)2+]eq
A475
1
2
3
4
5
6
7
Slope of line (A475 vs. [Fe(SCN)2+]) = ε =
1. Abso
ance measurements to determine the Equili
ium Constant (20 pts)
Test Tube #
[Fe(SCN)2+]eq
A475
10
11
12
13
14
15
16
17
18
19
1. Calculation of the Equili
ium Constant Keq (called Kc in the text) (30 pts)
Test Tube #
[Fe3+]initial
[SCN-]initial
[FeSCN2+ ]eq
[Fe3+ ]eq
[SCN- ]eq
keq
10
11
12
13
14
15
16
17
18
19
Average value for Keq =
Questions (10 pts)
· Explain in the context of Le Chatelier's Principle why it is mathematically acceptable to assume that the initial concentration of the iron (III) ion, [Fe3+], is equal to the equili
ium concentration of the complex ion, [FeSCN2-], for the Beer’s Law determination (Part 2).
· If the class results for the were generally lower than the established value for Keq for this reaction, what might have caused the value to vary. This would seem to be a result of inaccuracies in the reported (labeled) concentrations of the reagents. What specific inaccuracies might have cause the generally lower values in the class results. Explain your answer. This is a mathematical question and requires a mathematical answer.
Results
1
Qualitative examination of equili
ia and Le Chatelier's Principle
Well | Contents (drops) | Observations
|| FeO 3] Mo color chanse, clear Ligued
2 KSCN [3]
No dor change, cleer isu d
Fe(NOW: [1VKSCN 1]
Solation Ained orange
Fe(NOu): [2/KSCN [2]
Fe(NOs)s [3YKSCN [3]
Ugh orange gobo
| Orange coludion
For 6-13 all wells start with:
Fe(NOy), [3/KSCN [3]
Distilled water [2] (control)
| chear—sobation 00 change gitubion EN ee
HiS04 [2]
7 | Fe(NOs) [2] no change, solubim dx dae orange
8 Kscn) no change
9 | Kson fg no change
10 |Ksont, IM) B lukon changed dom ormnge Av Sn
| NaHPOL [2] orange Ao des golden
2 oranse “ho cles Solution
KSCN [1, IMJH:SO4 [3]
orange to reddich-orange solubion
Tor 14-18 materials are:
0.0025M Fe(NO3),/0-1M HNO IM KSCN
As above 1/4/4
orange solukim
15 | Asabove 23/4 Ak cranae solakion
16 | Asabove 32/4 eMich orange soluion
17 | Asabove ana Jacle- vec. oranga_silotion
18 As above 5/0/4
ced solabm (deb)
2. Beer's Law Abso
ance Data (Abso
ance of Fe(SCN)™")
Bring these data to my desk before continuing to Part 3.
[Test Tube # | Ae
1 0.091 .
2 0-144 ~
[3 | omy |
4 0.248 } _
s 0-207 _
6 0-460 .
7 0-55
3. Abso
ance data to determine the Equili
ium Constant
Do not expect these measurements to be linear. There is no need for me to see them during the lab.
Test Tube # Asse
0 S¥ oma
| mn oan
2 0-394
XXXXXXXXXX -
14 0.26%
| 15 0-4dy
XXXXXXXXXX
XXXXXXXXXX
18 0386
Lr los |