Determination of the molar Volume of a Gas at STP

Summary

In this experiment, the molar volume of hydrogen at standard temperature and pressure (STP) is determined by reacting magnesium metal with hydrochloric acid. A magnesium strip is secured with copper wire to prevent reactions during the process. Hydrochloric acid is carefully added to a gas collection tube, where hydrogen gas is generated and collected via water displacement. After the reaction, the hydrogen gas is allowed to equilibrate with the surrounding temperature before measuring its volume. This process incorporates adjustments for atmospheric and water vapor pressures, highlighting key experimental techniques in gas collection.

Takeaways

• 🔬 The experiment aims to determine the molar volume of hydrogen gas at standard temperature and pressure (STP).
• 🧪 Magnesium metal reacts with hydrochloric acid to produce hydrogen gas.
• ⚖️ A strip of magnesium with a mass of 0.0342 grams is used for the reaction.
• 🔗 Copper wire is employed to hold the magnesium ribbon in place during the experiment.
• 💧 Hydrochloric acid is carefully mixed with water in a gas collection tube to facilitate the reaction.
• 🌡️ The hydrogen gas is collected through water displacement, allowing for accurate volume measurement.
• 🕒 After the reaction, the collected hydrogen gas is allowed to equilibrate with the surrounding air temperature.
• 🌊 The gas collection tube is adjusted in a water tank to ensure equal water levels inside and outside for pressure measurement.
• 📏 The volume of the hydrogen gas is recorded after achieving equilibrium in pressure with the atmosphere.
• 🌬️ Corrections for water vapor pressure are made by measuring the temperature of the water in the tank.

Q & A

What is the objective of the experiment?

The objective is to determine the molar volume of hydrogen gas generated from the reaction of magnesium metal with hydrochloric acid at standard temperature and pressure (STP).

What materials are used in this experiment?

The materials used include magnesium metal, hydrochloric acid, copper wire, a graduated gas collection tube, and water.

Why is copper wire used in the experiment?

Copper wire is used to hold the magnesium ribbon in place during the reaction because it does not react with hydrochloric acid.

How is the hydrogen gas collected during the experiment?

Hydrogen gas is collected through the displacement of water in the gas collection tube as it is produced from the reaction.

What precautions are taken when adding hydrochloric acid to the gas collection tube?

Hydrochloric acid is added carefully while keeping the tube inclined to layer it under the water, preventing mixing until the magnesium is inserted.

What happens when hydrochloric acid reaches the magnesium metal?

When hydrochloric acid reaches the magnesium metal, it reacts to produce hydrogen gas.

How is the pressure inside the gas collection tube measured?

The pressure inside the tube is determined by equalizing the water levels inside and outside the tube, reflecting the barometric or atmospheric pressure.

What is done after the magnesium has completely reacted?

After the magnesium has completely reacted, the hydrogen gas is allowed to stand for a few minutes to reach the same temperature as the surrounding air.

Why is it important to correct for the pressure of water vapor?

Correcting for the pressure of water vapor is important to accurately determine the volume of hydrogen gas collected, as water vapor exerts its own pressure.

What principles does this experiment illustrate?

The experiment illustrates principles of gas collection by displacement and the relationships outlined in gas laws, specifically regarding pressure, volume, and temperature.