Temperature Dependence

Source: Smaa Koraym at Johns Hopkins University, MD, USA

1. Preparation of 0.5 M Fe(NO₃)₃Expand

   Here, we show the preparation of a solution for 10 students working in pairs, with some excess. Please adjust quantities as needed.

   • To set up for this lab experiment, wear the appropriate personal protective equipment, including a lab coat, chemical splash goggles, and gloves
   • Prepare 250 mL of a 0.5 M aqueous solution of iron (III) nitrate. Measure out 50.5 g of iron nitrate nonahydrate on a top-loading balance. Place a powder funnel in the mouth of a 250-mL Erlenmeyer flask and pour the iron (III) nitrate nonahydrate into it.
   • Measure out 175 mL of deionized water with a graduated cylinder and pour it into the flask.
   • Remove the funnel, place a stir bar in the flask, and start stirring the mixture on a stir plate. While the mixture stirs, label a 250-mL polyethylene bottle as ‘0.5 M Fe(NO₃)₃’.
   • Once the solution appears homogeneous, place the funnel back in the flask and add another 75 mL of deionized water.
   • Continue stirring until the solution appears homogeneous again. Then, turn off the stir motor and remove the stir bar from the flask.
   • Transfer the solution into the polyethylene bottle. Store the capped bottle at the back of the instructor's hood until just before the lab.
   • Lastly, wash your glassware and equipment and put away the iron (III) nitrate nonahydrate.
2. Preparation of the LaboratoryExpand
   • Place a labeled waste container for aqueous iron solutions in the back of the hood.
   • Make sure each workstation is equipped with a hotplate and a support rod, a medium 3-prong clamp, and a thermometer clamp. Attach both clamps to the support rod, and confirm that the vacuum sources are equipped with silicone tubing.
   • Ensure that each sink has plenty of paper towels.
   • Assemble the gas pressure sensor devices. Confirm that the devices are charged and working before distributing them to the workstations.
   • Make sure two locking tapered stopper adapters are tightly attached to the flexible polymer tubing and set one at each workstation along with a 20-mL Luer-Lok syringe, a two-way locking stopcock, and a number five 2-hole rubber stopper.
   • Set out the following equipment and glassware at each lab station (we suggest that students work in pairs):

     1    20-mL volumetric pipette

     1    Pipette controller

     1    50-mL beaker

     1    100-mL beaker

     3    400-mL beakers

     1    600-mL beaker

     1    125-mL Büchner flask

     1    Roll of lab tape

     1    Labeling pen

     1    Glass thermometer

   • Fill a 125-mL wash bottle with deionized water, and set one at each workstation.
   • Shortly before the lab, fill an insulated cooler or bucket with crushed or chipped ice. Place the cooler in a central area.
   • Finally, place a 1-L bottle of 3 wt% hydrogen peroxide in the central hood.