Gasstoichiometrie mit Magnesium

Berechnung des Molvolumens durch Reaktion von Mg mit HCl

Gas Laws Intermediate (High School) 40 Min. ~$8,00

Ziel

Das Molvolumen von Wasserstoffgas bei Raumtemperatur bestimmen, indem eine bekannte Masse Magnesiumband mit überschüssiger Salzsäure zur Reaktion gebracht wird.

Hintergrund

When magnesium reacts with HCl, hydrogen gas is produced: Mg + 2HCl → MgCl₂ + H₂. By measuring the mass of Mg used and the volume of H₂ collected, the molar volume at room conditions can be calculated and compared with the theoretical value at STP (22.4 L/mol).

Sicherheitswarnungen

  • HCl is corrosive
  • Hydrogen is flammable — no flames
  • Handle glassware carefully

Erforderliche PSA

goggles gloves lab_coat

Materialien

  • Magnesium ribbon (0.1 g)
    Accurately weighed
  • Hydrochloric acid (HCl) (30 mL)
    2M, excess
  • Distilled water (500 mL)

Ausrüstung

Eudiometer tube or graduated cylinder (50 mL) Pneumatic trough Copper wire cage Rubber stopper Analytical balance Thermometer Barometer

Durchführung

1

Weigh a 3-4 cm strip of magnesium ribbon accurately. Record mass to 0.001 g.

3 Min.
2

Roll the Mg ribbon and secure it in a copper wire cage attached to a rubber stopper.

3 Min.
3

Fill the eudiometer tube with 2M HCl. Insert the stopper+Mg assembly, inverting the tube into the trough.

5 Min. Handle acid carefully
4

Allow the reaction to complete. All the Mg should dissolve, producing H₂ gas that collects at the top.

10 Min. No flames nearby
5

Equalize water levels inside and outside the tube. Read the gas volume at the meniscus.

3 Min.
6

Record room temperature and atmospheric pressure.

2 Min.
7

Correct for water vapor pressure. Calculate moles of H₂ from Mg mass. Determine molar volume.

8 Min.

Erwartete Ergebnisse

0.1 g Mg = 0.00411 mol, producing 0.00411 mol H₂. At room conditions (~25°C, 1 atm), volume should be about 100 mL. Calculated molar volume at STP should be approximately 22.4 L/mol (±5%).

Aufräumen

Neutralize remaining HCl with NaHCO₃. Dispose down the drain. Rinse all equipment.

Details

Kategorie
Gas Laws
Schwierigkeit
Intermediate (High School)
Dauer
40 Min.
Geschätzte Kosten
$8,00
Schritte
7
Materialien
3

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Frequently Asked Questions

What is the objective of Gasstoichiometrie mit Magnesium?
Das Molvolumen von Wasserstoffgas bei Raumtemperatur bestimmen, indem eine bekannte Masse Magnesiumband mit überschüssiger Salzsäure zur Reaktion gebracht wird.
How difficult is Gasstoichiometrie mit Magnesium?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Gasstoichiometrie mit Magnesium?
Key safety precautions include: HCl is corrosive; Hydrogen is flammable — no flames; Handle glassware carefully.
What materials are needed for Gasstoichiometrie mit Magnesium?
The main materials required are: Magnesium ribbon, Hydrochloric acid (HCl), Distilled water.
What results should I expect from Gasstoichiometrie mit Magnesium?
0.1 g Mg = 0.00411 mol, producing 0.00411 mol H₂. At room conditions (~25°C, 1 atm), volume should be about 100 mL. Calculated molar volume at STP should be approximately 22.4 L/mol (±5%).