Lab Procedure:
You will be working with strongly acidic and basic solutions in this lab. Safety glasses
must be worn at all times and gloves should always be used when handling solutions.
Precipitating Fe(OH)3:
1. Using a 10 mL volumetric pipet, add 10 mL of acidic 0.05M Fe(NO3)3 solution to
each of three test tubes. (small flasks also work well)
2. Fill a 50 mL burette with 0.05M NaOH.
3. Slowly add base to the iron solution until a red-brown precipitate appears and
remains upon stirring.
4. After 10 minutes, check to see that solid remains in the flask. If it has all
redissolved, add a bit more base.
5. After your solutions have reached equilibrium. Centrifuge your samples to settle
all the ppt to the bottom of the tubes.
6. Measure and record the pH of each solution with a pH meter.
7. When directed by the lab instructor, take your solutions to the AA to be tested.
Calibration Curve:
• Normally, I would have you create your own calibration curve.
• We only have one AA, therefore the following solutions will be prepared for you.
• You must:
i. Calculate the [Fe3+]
ii. measure the Abs
iii. Create the actual calibration curve plot.
• Y-axis = Abs
• X-axis = [Fe3+]
iv. Determine the best fit function for the data.
• Linear
• 2nd order Polynomial
• Make sure to attach both plots
mL of 0.10 M Fe3+ mL of 0.05 M
HNO3 [Fe3+] Abs
15 Dilute to 25 mL
10 Dilute to 25 mL
5 Dilute to 25 mL
2 Dilute to 25 mL
1 Dilute to 25 mL
put
flask
On
blankpp.
#
fel0H3()
Fe
+
30H
isa)
k3p
=
[Fe3+]2017-3
↑
1
is
ove
PJH
PH
0.84
1.849
8.82
1.825
0.87
1,084
8.885
8,989
