Pelarutan Tidak Selalu Eksotermik

Membandingkan perubahan suhu pelarutan garam berbeda

Thermochemistry Beginner (Middle School) 25 menit ~$8,00

Tujuan

Bandingkan entalpi pelarutan garam berbeda (NaOH, CaCl₂, NH₄NO₃, KNO₃) untuk menunjukkan bahwa pelarutan bisa bersifat eksotermik atau endotermik.

Latar Belakang

Students often assume dissolving always releases heat. This experiment tests four salts: NaOH and CaCl₂ dissolve exothermically (temperature rises), while NH₄NO₃ and KNO₃ dissolve endothermically (temperature drops). The results illustrate that lattice energy vs hydration energy determines the sign of ΔH.

Peringatan Keselamatan

  • NaOH is extremely corrosive
  • NH₄NO₃ is an oxidizer
  • Wear goggles and gloves

APD yang Diperlukan

goggles gloves

Bahan

  • Sodium hydroxide pellets (10 g)
    Exothermic
  • Calcium chloride (10 g)
    Exothermic
  • Ammonium nitrate (10 g)
    Endothermic
  • Potassium nitrate (10 g)
    Endothermic
  • Distilled water (400 mL)

Peralatan

4 polystyrene cups Thermometer Stirring rod Analytical balance

Prosedur

1

Add 100 mL water to each of four labeled cups. Record the initial temperature of each.

5 menit
2

Add 10 g NaOH to cup 1. Stir and record the maximum temperature.

3 menit Very exothermic — NaOH is corrosive
3

Add 10 g CaCl₂ to cup 2. Stir and record the maximum temperature.

3 menit
4

Add 10 g NH₄NO₃ to cup 3. Stir and record the minimum temperature.

3 menit
5

Add 10 g KNO₃ to cup 4. Stir and record the minimum temperature.

3 menit
6

Create a table ranking the salts from most exothermic to most endothermic.

3 menit
7

Discuss why some dissolve exothermically and others endothermically (lattice energy vs hydration energy).

5 menit

Hasil yang Diharapkan

NaOH: +15-20°C rise. CaCl₂: +10-15°C rise. NH₄NO₃: -15-20°C drop. KNO₃: -5-10°C drop. Clear demonstration that dissolution can be either exothermic or endothermic.

Pembersihan

NaOH and CaCl₂ solutions should be neutralized before disposal. All solutions can be poured down the drain after dilution.

Detail

Kategori
Thermochemistry
Tingkat Kesulitan
Beginner (Middle School)
Durasi
25 menit
Perkiraan Biaya
$8,00
Langkah
7
Bahan
5

Eksperimen Lainnya

Demonstrasi Reaksi Endotermik 20 min 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 Simulasi Kalorimetri Bom 45 min Verifikasi Hukum Hess 60 min

Frequently Asked Questions

What is the objective of Pelarutan Tidak Selalu Eksotermik?
Bandingkan entalpi pelarutan garam berbeda (NaOH, CaCl₂, NH₄NO₃, KNO₃) untuk menunjukkan bahwa pelarutan bisa bersifat eksotermik atau endotermik.
How difficult is Pelarutan Tidak Selalu Eksotermik?
This experiment is rated as Beginner (Middle School). It takes approximately 25 minutes to complete.
What safety precautions are needed for Pelarutan Tidak Selalu Eksotermik?
Key safety precautions include: NaOH is extremely corrosive; NH₄NO₃ is an oxidizer; Wear goggles and gloves.
What materials are needed for Pelarutan Tidak Selalu Eksotermik?
The main materials required are: Sodium hydroxide pellets, Calcium chloride, Ammonium nitrate, Potassium nitrate, Distilled water.
What results should I expect from Pelarutan Tidak Selalu Eksotermik?
NaOH: +15-20°C rise. CaCl₂: +10-15°C rise. NH₄NO₃: -15-20°C drop. KNO₃: -5-10°C drop. Clear demonstration that dissolution can be either exothermic or endothermic.