镁的气体化学计量学

通过Mg与HCl反应计算摩尔体积

Gas Laws Intermediate (High School) 40 分钟 ~$8.00

目标

通过已知质量的镁条与过量盐酸反应，测定室温条件下氢气的摩尔体积。

背景

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).

安全警告

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

所需PPE

goggles gloves lab_coat

材料

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

设备

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

步骤

1

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

3 分钟
2

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

3 分钟
3

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

5 分钟 Handle acid carefully
4

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

10 分钟 No flames nearby
5

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

3 分钟
6

Record room temperature and atmospheric pressure.

2 分钟
7

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

8 分钟

预期结果

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%).

清理

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

详情

类别
Gas Laws
难度
Intermediate (High School)
时长
40 分钟
预估费用
$8.00
步骤数
7
材料
3

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Frequently Asked Questions

What is the objective of 镁的气体化学计量学?
通过已知质量的镁条与过量盐酸反应，测定室温条件下氢气的摩尔体积。
How difficult is 镁的气体化学计量学?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for 镁的气体化学计量学?
Key safety precautions include: HCl is corrosive; Hydrogen is flammable — no flames; Handle glassware carefully.
What materials are needed for 镁的气体化学计量学?
The main materials required are: Magnesium ribbon, Hydrochloric acid (HCl), Distilled water.
What results should I expect from 镁的气体化学计量学?
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%).