S120: Prep Notes
Introduction
The reaction of zinc metal with iodine shows direct combination, decomposition, recrystallization of sublimed I2, and electrolysis.
Zn(s) + I2(s) → No Reaction
Zn(s) + I2(s) H2O→ ZnI2(aq)
Zn2+ + 2I- → Zn + I2
Supplies
Short List
- 250 or 400mL beaker
- 100mm petri dish
- Two 15cm insulated copper wires
- Funnel, filter paper, and flask
- Stirring rob
- DC power source (9V battery)
- Distilled water
- Goggles and gloves
Chemicals
- 6g Zn dust
- 4g I2 crystals
Prior to Lecture (prep time ~ 10 min.)
1. Assemble the following equipment:
- Two 150 mL beakers, with a glass funnel with filter paper dampened
- 100mm petri dish
- Two 15cm insulated copper wires w/alligator clips to attach to battery
- Two 8cm copper wire folded in half
- Stirring rod
- DC power source
2. Distilled Water
Prepare the following chemicals if vials are not filled
- 6g zinc dust
- 4g I2 crystals
To Conduct Demonstration
- Mix Zn and I2 in a dry beaker on the overhead projector (no reaction).
- Add 40mL of di water a bit of a time with ventilation (copious violet fumes of iodine).
- Stir the mixture well and filter. Pour filtrate into the petri dish (clear, colorless solution).
- Connect copper wires to the DC source. Place the wires in the petri dish so that they are well-separated and immersed in solution. Turn on the power supply. (Amber coloration at anode, zinc accumulation on cathode).
Demo Time: ~4 minutes
Safety and Disposal
Perform in a well-ventilated room to avoid breathing iodine vapors. Copper wires can be cleaned off and reused. Place filter with filtrate and tag for EH&S (possible waste container for filtrate in Demo room). Pour liquid contents into Qual drum in lab M124.