Exotherme Kristallisation von Natriumacetat

Messung der bei spontaner Kristallisation freigesetzten Wärme

Thermochemistry Intermediate (High School) 30 Min. ~$8,00

Ziel

Die bei der Kristallisation von übersättigtem Natriumacetat freigesetzte Wärme kalorimetrisch quantifizieren.

Hintergrund

When supersaturated sodium acetate crystallizes, it releases stored energy as heat. By triggering crystallization inside a calorimeter and measuring the temperature rise, the enthalpy of crystallization can be determined. This is the same principle used in reusable hand warmers.

Sicherheitswarnungen

  • Hot solution during preparation
  • Crystallization releases heat — container gets warm

Erforderliche PSA

goggles

Materialien

  • Sodium acetate trihydrate (80 g)
  • Distilled water (150 mL)

Ausrüstung

Polystyrene cup calorimeter Hot plate Thermometer Beaker (250 mL) Stirring rod

Durchführung

1

Dissolve 80 g sodium acetate trihydrate in 20 mL water by heating to about 70°C. Stir until clear.

8 Min. Handle hot solution carefully
2

Pour the solution into the polystyrene cup calorimeter. Allow to cool undisturbed to room temperature.

15 Min.
3

Record the temperature of the supersaturated solution.

1 Min.
4

Add a single small crystal of sodium acetate to trigger crystallization. Immediately stir gently and record temperature every 15 seconds.

3 Min.
5

Record the maximum temperature reached.

1 Min.
6

Calculate the heat released: q = mcΔT. Determine ΔH of crystallization per mole.

5 Min.

Erwartete Ergebnisse

Temperature should rise 15-25°C above room temperature. The enthalpy of crystallization is approximately -19.7 kJ/mol for sodium acetate trihydrate. Measured values should be within 20% of this.

Aufräumen

The sodium acetate can be remelted and reused. Rinse the calorimeter. Non-toxic — can go down the drain.

Details

Kategorie
Thermochemistry
Schwierigkeit
Intermediate (High School)
Dauer
30 Min.
Geschätzte Kosten
$8,00
Schritte
6
Materialien
2

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Frequently Asked Questions

What is the objective of Exotherme Kristallisation von Natriumacetat?
Die bei der Kristallisation von übersättigtem Natriumacetat freigesetzte Wärme kalorimetrisch quantifizieren.
How difficult is Exotherme Kristallisation von Natriumacetat?
This experiment is rated as Intermediate (High School). It takes approximately 30 minutes to complete.
What safety precautions are needed for Exotherme Kristallisation von Natriumacetat?
Key safety precautions include: Hot solution during preparation; Crystallization releases heat — container gets warm.
What materials are needed for Exotherme Kristallisation von Natriumacetat?
The main materials required are: Sodium acetate trihydrate, Distilled water.
What results should I expect from Exotherme Kristallisation von Natriumacetat?
Temperature should rise 15-25°C above room temperature. The enthalpy of crystallization is approximately -19.7 kJ/mol for sodium acetate trihydrate. Measured values should be within 20% of this.