Estequiometria de Gases com Magnésio

Cálculo do volume molar pela reação de Mg com HCl

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

Objetivo

Determinar o volume molar do gás hidrogênio nas condições ambientais fazendo reagir uma massa conhecida de fita de magnésio com excesso de ácido clorídrico.

Contexto

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).

Avisos de segurança

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

EPI necessário

goggles gloves lab_coat

Materiais

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

Equipamentos

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

Procedimento

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%).

Limpeza

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

Detalhes

Categoria
Gas Laws
Dificuldade
Intermediate (High School)
Duração
40 min
Custo estimado
$8,00
Passos
7
Materiais
3

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Frequently Asked Questions

What is the objective of Estequiometria de Gases com Magnésio?
Determinar o volume molar do gás hidrogênio nas condições ambientais fazendo reagir uma massa conhecida de fita de magnésio com excesso de ácido clorídrico.
How difficult is Estequiometria de Gases com Magnésio?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Estequiometria de Gases com Magnésio?
Key safety precautions include: HCl is corrosive; Hydrogen is flammable — no flames; Handle glassware carefully.
What materials are needed for Estequiometria de Gases com Magnésio?
The main materials required are: Magnesium ribbon, Hydrochloric acid (HCl), Distilled water.
What results should I expect from Estequiometria de Gases com Magnésio?
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%).