Materials Needed

• Beaker
• Ice bath
• Fume hood
• Concentrated HNO₃ (nitric acid)
• Concentrated H₂SO₄ (sulfuric acid)
• Toilet paper (1 square)
• Beaker filled with water
• Tap water
• Hanging apparatus (for drying)

Procedure

1. Preparation of Nitrate Mixture:

• In a beaker placed in an ice bath, mix concentrated HNO₃ and concentrated H₂SO₄ in a 1:2 ratio.
• Allow the mixture to cool.

1. Immersion of Toilet Paper:

• Immerse one square of toilet paper into the cooled acid mixture for 30 seconds.

1. Neutralization and Rinsing:

• Immediately remove the toilet paper and place it in a beaker filled with water.
• Let the paper sit in water for about 2 minutes.
• Rinse the paper under tap water.

1. Drying:

• Hang the rinsed toilet paper to dry completely.

1. Ignition:

• Once dry, ignite the flash paper to demonstrate its rapid combustion.

Safety Precautions

• Conduct the experiment in a fume hood to avoid inhaling fumes from the acids.
• Wear appropriate personal protective equipment (PPE), including gloves and goggles.
• Handle concentrated acids with care to avoid spills and skin contact.

This experiment demonstrates the preparation of flash paper, the principles of nitration and combustion.

Flash Paper Alternative Procedure

Flash Paper
Demo # Gen.35

Equipment

• Tissue paper
• Tongs
• Paper towels
• 250 mL beaker
• Ice bath

Chemicals

• 70 mL of concentrated sulfuric acid
• 30 mL of concentrated nitric acid
• 250 mL of 1 M sodium hydrogen carbonate (NaHCO₃)

Procedure

Prepare Acid Mixture:

• Place a 250 mL beaker in an ice bath.
• Add 70 mL of concentrated sulfuric acid and 30 mL of concentrated nitric acid to the beaker.

Prepare Tissue Paper:

• Cut the tissue paper into approximately 2-inch squares.

Immerse in Acid:

• Using tongs, immerse each piece of tissue paper in the acid mixture for about one minute.

Rinse:

• Rinse each piece of paper in three successive 500 mL water baths. Use fresh water for each piece.

Neutralize:

• Immerse each piece of paper in 250 mL of 1 M NaHCO₃.
• If substantial bubbling occurs, re-rinse in water and neutralize in NaHCO₃ again.

Dry:

• Spread the treated paper on paper towels to dry overnight.

Demonstration

• To demonstrate the burning of flash paper, light a candle or Bunsen burner and throw the paper into the flame.
• Observation: The flash paper burns very quickly and leaves, at most, a tiny residue of white ash.

Safety Note

• Large amounts of flash paper should not be stored for any length of time.