Ni & Cu Coordination Complexes
• Hand in: Pre-Lab, OPEN EXCEL
• Today, we will study the reactions of different
coordination complexes with ethylenediamine to
determine if minor differences in structure make
a difference in chemical reaction
2+
OH2
H2O
H2O
OH2
Ni
OH2
OH2
2+
OH2
H2O
H2O
Cu
OH2
OH2
OH2
Ni(H2O)6+2
Cu(H2O)6+2
Ni & Cu Coordination Complexes
Let’s consider the reaction between
+2
¨ CH CH ¨NH
Ni(H2O)
+
H N
6
2
2 2 2
2+
OH2
H2O
H2O
Ni
OH2
OH2
+
N
..
H2O
..
H2NCH2CH2NH2
H2O
OH2
Ni(H2O)6+2
N
N
Ni
N
N
Ni
2+
N
OH2
+ 2H2O
OH2
+
ethylenediamine (en)
Ni(en)3 +2
N coordination
complex after
N
three additions
of en
N
–
N
first step
= H2NCH2CH2NH2
What will happen with Copper Complex’s slightly different geometry??
Ni & Cu Coordination Complexes
For the Experiment:
1.
Set up Data Collection and Graph in EXCEL,
a.
on the x axis: Time (in secs) collect data every 10 secs
b.
on the y axis: Temp (oC) – note temperature change, when temperature
is stable and not decreasing, add next volume of (en)
c.
Graph Live so you know when to add the next (en)
2.
Prepare Equipment
a.
Coffee Cup Calorimeter
b.
Thermometer from Drawer
3.
Obtain Reagents – WRITE DOWN CONC. ON BOTTLES
ALL VOLUMES MUST BE EXACT!!!!
a.
Trial 1 - Nickel Complex – GREEN
b.
Ethylenediamine (en) – IN FUME HOOD
WEAR GLOVES
DISPENSE INTO A TEST TUBE AND COVER WITH PAPER
ADD EN UNTIL NO CHANGE IS NOTED IN TEMP. (No more than 4 steps
for either Trial)
c.
Trial 2 – Copper Complex – BLUE
Ni & Cu Coordination Complexes
4.
Actual Experiment
a.
obtain baseline temperature data for at least one to two
minutes
b.
add (en)
c.
immediately cover and gently swirl
d.
collect data until temperature plateaus
e.
try not to let temperature drop
f.
add next (en) to the solution and repeat until temp no longer
rises (no more than 4 (en) additions per trial).
5.
SAVE YOUR DATA, RENAME!!!, and go to trial 2 with Cu +2 complex
6.
ALL WASTE IN LARGE CONTAINER IN FUME HOOD
Ni & Cu Coordination Complexes – Graphing in EXCEL
(page 4 step 3)
Temperature (oC)
Thermo-Profile of the Nickel Coordination Complex
25.8
25.6
25.4
25.2
25.0
24.8
24.6
24.4
24.2
24.0
23.8
23.6
23.4
23.2
23.0
22.8
22.6
22.4
22.2
22.0
21.8
21.6
21.4
21.2
0
50
100
150
200
250
300
350
400
450
500
550
Time (seconds)
 38
. J   11
. g
 x
qrxn   
 x mL of each step x (T f  Ti )

 g o C   mL 
H 
qrxn
mol en
600
650
700
750
Ni & Cu Coordination Complexes –
Calculations in EXCEL (Table on Page 5)
Data Table to be generated in EXCEL by students:
Reaction of Ni
Ti
Tf
T
V(soln)
m(soln)
S
Step 1
3.8
Step 2
3.8
Step 3
3.8
qrxn (J)
mol en
H (kJ/mol)
0.00750
Average
Reaction of Cu
Ti
Tf
T
V(soln)
m(soln)
S
Step 1
3.8
Step 2
3.8
Step 3
3.8
qrxn (J)
mol en
Average
H (kJ/mol)
Ni & Cu Coordination Complexes
What to do with the data?
q rxn = - (3.8 J/g oC ) x masssol. x (Tf – Ti)
Where:
q rxn
= energy released by the reaction
mass sol. = TOTAL mass of liquid in the calorimeter
Tf
= Final Temperature in the STEP
Ti
= Initial Temp in the STEP
So:
Then:
mass sol. = density of liquid (g/mL) x mL of TOTAL soln.
H 
qrxn
mol en
Where:
ΔH
= Heat of reaction (kJoules/mole)
mol (en) = moles of en in the STEP
WATCH YOUR UNITS = Joules or Kilojoules!!!!
Lab Report
 Title Page
 Purpose
 Results
- Two Graphs (page 5, #1)
Ni(H20)6+2 and ethylenediamine
Cu(H20)6+2 and ethylenediamine
- EXCEL Table, page 5, #2, (with sample calculations for Ni and Cu)
- Present/Staple in order data/calculations were obtained/performed
- Significant Figures and Units
- Precision and Accuracy
 Conclusion
Avg ΔH for Ni reaction and Avg ΔH for Cu reaction
Number of en’s per Ni complex (question #3, page 5)
Number of en’s per Cu complex (question #3, page 5)
Errors and Improvements
 Individual Checked-Pre-labs