Demonstrasi Reaksi Endotermik

Reaksi dingin barium hidroksida dan amonium tiosianat

Thermochemistry Intermediate (High School) 20 menit ~$12,00

Tujuan

Demonstrasikan reaksi yang sangat endotermik di mana campuran menjadi cukup dingin untuk membekukan air di bagian luar labu.

Latar Belakang

When barium hydroxide octahydrate reacts with ammonium thiocyanate, the temperature drops to approximately -20°C. This endothermic reaction absorbs so much heat from the surroundings that water on the outside of the flask freezes, effectively gluing the flask to a wet board.

Peringatan Keselamatan

  • Barium compounds are toxic if ingested
  • Ammonia gas is released — work in fume hood or ventilated area
  • Wear gloves when handling barium hydroxide
  • Do not inhale the ammonia fumes

APD yang Diperlukan

goggles gloves lab_coat

Bahan

  • Barium hydroxide octahydrate (32 g)
    Toxic
  • Ammonium thiocyanate (16 g)
  • Water (5 mL)
    On the board

Peralatan

250 mL Erlenmeyer flask Wooden board Thermometer Stirring rod

Prosedur

1

Pour a few drops of water onto the wooden board to create a wet spot.

1 menit
2

Add 32 g barium hydroxide octahydrate to the flask.

2 menit Wear gloves — barium is toxic
3

Add 16 g ammonium thiocyanate to the flask. Stir the mixture with a glass rod.

2 menit Ammonia released — ventilation
4

Place the flask on the wet spot on the board. Insert the thermometer.

1 menit
5

Observe the temperature dropping dramatically. Record the minimum temperature.

5 menit Do not inhale fumes
6

After 5 minutes, try to lift the flask. It should be frozen to the board.

2 menit
7

Explain that the reaction absorbed heat from the surroundings, freezing the water beneath.

2 menit

Hasil yang Diharapkan

The temperature should drop to approximately -20°C within minutes. The flask should freeze to the wet board. A strong smell of ammonia confirms the reaction is proceeding.

Pembersihan

Allow to warm to room temperature. Dispose of barium waste in heavy metal waste container. Rinse flask and ventilate area thoroughly.

Detail

Kategori
Thermochemistry
Tingkat Kesulitan
Intermediate (High School)
Durasi
20 menit
Perkiraan Biaya
$12,00
Langkah
7
Bahan
3

Eksperimen Lainnya

Entalpi Fusi Es 25 min Kalorimetri Cangkir Kopi 40 min Kapasitas Panas Spesifik Logam 40 min Kimia Kompres Dingin 20 min Kristalisasi Eksotermik Natrium Asetat 30 min Panas Pembakaran Magnesium 50 min Pelarutan Tidak Selalu Eksotermik 25 min Simulasi Kalorimetri Bom 45 min Verifikasi Hukum Hess 60 min

Frequently Asked Questions

What is the objective of Demonstrasi Reaksi Endotermik?
Demonstrasikan reaksi yang sangat endotermik di mana campuran menjadi cukup dingin untuk membekukan air di bagian luar labu.
How difficult is Demonstrasi Reaksi Endotermik?
This experiment is rated as Intermediate (High School). It takes approximately 20 minutes to complete.
What safety precautions are needed for Demonstrasi Reaksi Endotermik?
Key safety precautions include: Barium compounds are toxic if ingested; Ammonia gas is released — work in fume hood or ventilated area; Wear gloves when handling barium hydroxide.
What materials are needed for Demonstrasi Reaksi Endotermik?
The main materials required are: Barium hydroxide octahydrate, Ammonium thiocyanate, Water.
What results should I expect from Demonstrasi Reaksi Endotermik?
The temperature should drop to approximately -20°C within minutes. The flask should freeze to the wet board. A strong smell of ammonia confirms the reaction is proceeding.