Hess Yasasının Doğrulanması

Üç tepkime kullanarak entalpisinin durum fonksiyonu olduğunu kanıtlama

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

Hedef

Üç birbiriyle ilişkili tepkimenin entalpi değişimlerini ölçerek ΔH₁ + ΔH₂ = ΔH₃ olduğunu göstermek ve Hess yasasını doğrulamak.

Arka Plan

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.

Güvenlik Uyarıları

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

Gerekli KKD

goggles gloves lab_coat

Malzemeler

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

Ekipman

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

Prosedür

1

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

8 dak Exothermic — NaOH dissolving
2

Calculate ΔH1 for dissolution. Repeat for accuracy.

5 dak
3

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

8 dak
4

Calculate ΔH2 for neutralization.

5 dak
5

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

8 dak Very exothermic
6

Calculate ΔH3 for combined dissolution + neutralization.

5 dak
7

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

8 dak

Beklenen Sonuçlar

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

Temizlik

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

Ayrıntılar

Kategori
Thermochemistry
Zorluk
Advanced (University)
Süre
60 dak
Tahmini Maliyet
$15,00
Adımlar
7
Malzemeler
4

Daha Fazla Deney

Bomba Kalorimetresi Simülasyonu 45 min Buzun Erime Entalpisi 25 min Çözünme Her Zaman Ekzotermik Değildir 25 min Endotermik Tepkime Gösterisi 20 min Kahve Kupası Kalorimetresi 40 min Magnezyumun Yanma Isısı 50 min Metallerin Özgül Isı Kapasitesi 40 min Sodyum Asetatın Ekzotermik Kristallenmesi 30 min Soğuk Paket Kimyası 20 min

Frequently Asked Questions

What is the objective of Hess Yasasının Doğrulanması?
Üç birbiriyle ilişkili tepkimenin entalpi değişimlerini ölçerek ΔH₁ + ΔH₂ = ΔH₃ olduğunu göstermek ve Hess yasasını doğrulamak.
How difficult is Hess Yasasının Doğrulanması?
This experiment is rated as Advanced (University). It takes approximately 60 minutes to complete.
What safety precautions are needed for Hess Yasasının Doğrulanması?
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 Hess Yasasının Doğrulanması?
The main materials required are: Sodium hydroxide pellets, Hydrochloric acid (HCl), Sodium hydroxide solution, Distilled water.
What results should I expect from Hess Yasasının Doğrulanması?
ΔH1 (dissolution) ≈ -44 kJ/mol, ΔH2 (neutralization) ≈ -57 kJ/mol, ΔH3 (combined) ≈ -101 kJ/mol. ΔH1 + ΔH2 should equal ΔH3 within experimental error (±10%).