Panas Pembakaran Magnesium

Menentukan ΔH menggunakan hukum Hess dan magnesium oksida

Thermochemistry Advanced (University) 50 menit ~$12,00

Tujuan

Tentukan entalpi pembakaran magnesium secara tidak langsung menggunakan hukum Hess, karena pengukuran langsung tidak praktis.

Latar Belakang

The combustion of Mg in O₂ is too vigorous for direct calorimetry. Instead, we measure: (1) Mg + HCl → MgCl₂ + H₂, and (2) MgO + HCl → MgCl₂ + H₂O. Combined with the known ΔH for H₂ + 0.5O₂ → H₂O, Hess's law gives ΔH(combustion) of Mg.

Peringatan Keselamatan

  • HCl is corrosive
  • Mg + HCl produces flammable H₂ gas
  • Do not perform near open flames
  • Wear goggles and gloves

APD yang Diperlukan

goggles gloves lab_coat

Bahan

  • Magnesium ribbon (0.5 g)
  • Magnesium oxide (MgO) (1 g)
  • Hydrochloric acid (HCl) (200 mL)
    1M

Peralatan

Polystyrene cup calorimeter Thermometer Analytical balance Graduated cylinder Lid

Prosedur

1

Reaction 1: Add 50 mL 1M HCl to the calorimeter. Record temperature. Add 0.25 g Mg ribbon. Record max temperature.

8 menit H₂ produced — no flames
2

Calculate ΔH1 for Mg + 2HCl → MgCl₂ + H₂.

5 menit
3

Clean the calorimeter. Reaction 2: Add 50 mL 1M HCl. Record temperature. Add 0.5 g MgO. Record max temperature.

8 menit
4

Calculate ΔH2 for MgO + 2HCl → MgCl₂ + H₂O.

5 menit
5

Use Hess's law: ΔH(combustion) = ΔH1 - ΔH2 + ΔH(H₂ combustion). ΔH(H₂ + 0.5O₂ → H₂O) = -285.8 kJ/mol.

5 menit
6

Compare calculated ΔH with accepted value (-601.6 kJ/mol).

5 menit

Hasil yang Diharapkan

ΔH1 ≈ -462 kJ/mol, ΔH2 ≈ -146 kJ/mol. ΔH(comb) = -462 - (-146) + (-286) = -602 kJ/mol, close to the accepted -601.6 kJ/mol.

Pembersihan

Neutralize HCl waste. Dispose of MgCl₂ solution down the drain. Rinse calorimeter.

Detail

Kategori
Thermochemistry
Tingkat Kesulitan
Advanced (University)
Durasi
50 menit
Perkiraan Biaya
$12,00
Langkah
6
Bahan
3

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 Pelarutan Tidak Selalu Eksotermik 25 min Simulasi Kalorimetri Bom 45 min Verifikasi Hukum Hess 60 min

Frequently Asked Questions

What is the objective of Panas Pembakaran Magnesium?
Tentukan entalpi pembakaran magnesium secara tidak langsung menggunakan hukum Hess, karena pengukuran langsung tidak praktis.
How difficult is Panas Pembakaran Magnesium?
This experiment is rated as Advanced (University). It takes approximately 50 minutes to complete.
What safety precautions are needed for Panas Pembakaran Magnesium?
Key safety precautions include: HCl is corrosive; Mg + HCl produces flammable H₂ gas; Do not perform near open flames.
What materials are needed for Panas Pembakaran Magnesium?
The main materials required are: Magnesium ribbon, Magnesium oxide (MgO), Hydrochloric acid (HCl).
What results should I expect from Panas Pembakaran Magnesium?
ΔH1 ≈ -462 kJ/mol, ΔH2 ≈ -146 kJ/mol. ΔH(comb) = -462 - (-146) + (-286) = -602 kJ/mol, close to the accepted -601.6 kJ/mol.