Verifikasi Hukum Hess

Mengkonfirmasi bahwa entalpi adalah fungsi keadaan menggunakan tiga reaksi

Thermochemistry Advanced (University) 60 menit ~$15,00

Tujuan

Verifikasi hukum Hess dengan mengukur perubahan entalpi tiga reaksi yang berkaitan dan menunjukkan bahwa ΔH1 + ΔH2 = ΔH3.

Latar Belakang

Hess's law states that the total enthalpy change for a reaction is independent of the pathway. This is verified by measuring: (1) NaOH(s) → NaOH(aq), (2) NaOH(aq) + HCl(aq) → NaCl(aq), and (3) NaOH(s) + HCl(aq) → NaCl(aq). The sum ΔH1 + ΔH2 should equal ΔH3.

Peringatan Keselamatan

  • NaOH pellets are extremely corrosive and generate heat when dissolved
  • HCl is corrosive
  • Wear goggles and gloves throughout

APD yang Diperlukan

goggles gloves lab_coat

Bahan

  • Sodium hydroxide pellets (8 g)
    Anhydrous
  • Hydrochloric acid (HCl) (150 mL)
    1M
  • Sodium hydroxide solution (50 mL)
    1M
  • Distilled water (200 mL)

Peralatan

Polystyrene cup calorimeter (2 cups nested) Thermometer Analytical balance Graduated cylinder Stopwatch Lid with hole

Prosedur

1

Reaction 1: Add 50 mL distilled water to the calorimeter. Record temperature. Add 2 g NaOH pellets. Stir and record max temperature.

8 menit Exothermic — NaOH dissolving
2

Calculate ΔH1 for dissolution. Repeat for accuracy.

5 menit
3

Reaction 2: Add 50 mL 1M HCl to the calorimeter. Record temperature. Add 50 mL 1M NaOH. Record max temperature.

8 menit
4

Calculate ΔH2 for neutralization.

5 menit
5

Reaction 3: Add 50 mL 1M HCl to the calorimeter. Record temperature. Add 2 g NaOH pellets directly. Record max temperature.

8 menit Very exothermic
6

Calculate ΔH3 for combined dissolution + neutralization.

5 menit
7

Compare ΔH1 + ΔH2 with ΔH3. They should be approximately equal, verifying Hess's law.

8 menit

Hasil yang Diharapkan

ΔH1 (dissolution) ≈ -44 kJ/mol, ΔH2 (neutralization) ≈ -57 kJ/mol, ΔH3 (combined) ≈ -101 kJ/mol. ΔH1 + ΔH2 should equal ΔH3 within experimental error (±10%).

Pembersihan

Neutralize all solutions before disposal. Rinse calorimeter cups. Dry and store equipment.

Detail

Kategori
Thermochemistry
Tingkat Kesulitan
Advanced (University)
Durasi
60 menit
Perkiraan Biaya
$15,00
Langkah
7
Bahan
4

Eksperimen Lainnya

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Frequently Asked Questions

What is the objective of Verifikasi Hukum Hess?
Verifikasi hukum Hess dengan mengukur perubahan entalpi tiga reaksi yang berkaitan dan menunjukkan bahwa ΔH1 + ΔH2 = ΔH3.
How difficult is Verifikasi Hukum Hess?
This experiment is rated as Advanced (University). It takes approximately 60 minutes to complete.
What safety precautions are needed for Verifikasi Hukum Hess?
Key safety precautions include: NaOH pellets are extremely corrosive and generate heat when dissolved; HCl is corrosive; Wear goggles and gloves throughout.
What materials are needed for Verifikasi Hukum Hess?
The main materials required are: Sodium hydroxide pellets, Hydrochloric acid (HCl), Sodium hydroxide solution, Distilled water.
What results should I expect from Verifikasi Hukum Hess?
ΔH1 (dissolution) ≈ -44 kJ/mol, ΔH2 (neutralization) ≈ -57 kJ/mol, ΔH3 (combined) ≈ -101 kJ/mol. ΔH1 + ΔH2 should equal ΔH3 within experimental error (±10%).