Estequiometría de Gases con Magnesio

Cálculo del volumen molar por reacción de Mg con HCl

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

Objetivo

Determinar el volumen molar del gas hidrógeno en condiciones ambientales haciendo reaccionar una masa conocida de cinta de magnesio con exceso de ácido clorhídrico.

Antecedentes

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).

Advertencias de seguridad

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

EPP requerido

goggles gloves lab_coat

Materiales

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

Equipamiento

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

Procedimiento

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

Resultados esperados

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%).

Limpieza

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

Detalles

Categoría
Gas Laws
Dificultad
Intermediate (High School)
Duración
40 min
Costo estimado
$8,00
Pasos
7
Materiales
3

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Frequently Asked Questions

What is the objective of Estequiometría de Gases con Magnesio?
Determinar el volumen molar del gas hidrógeno en condiciones ambientales haciendo reaccionar una masa conocida de cinta de magnesio con exceso de ácido clorhídrico.
How difficult is Estequiometría de Gases con Magnesio?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Estequiometría de Gases con Magnesio?
Key safety precautions include: HCl is corrosive; Hydrogen is flammable — no flames; Handle glassware carefully.
What materials are needed for Estequiometría de Gases con Magnesio?
The main materials required are: Magnesium ribbon, Hydrochloric acid (HCl), Distilled water.
What results should I expect from Estequiometría de Gases con Magnesio?
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%).