CP1 Measuring the Molar Volume of a Gas

• What is the definition of molar volume of a gas?

  Volume occupied by one mole
• At STP, the molar volume of an ideal gas is approximately 22.4 dm³/mol.
• The round-bottom flask is used to contain the reaction mixture
• What is the purpose of a gas syringe in measuring molar volume?

  To measure gas volume
• Steps in the experimental procedure to measure molar volume of a gas

  1️⃣ Position the clamp stand and attach the round-bottom flask, ensuring it is connected to the gas syringe via tubing and sealed with a bung.

  2️⃣ Prepare Reactants: Measure the appropriate volume of liquid using a measuring cylinder and weigh the solid reactant using a balance.

  3️⃣ React Mix: Add the liquid to the round-bottom flask, then introduce the solid reactant. Quickly seal the bung.

  4️⃣ Collect Gas: Allow the reaction to proceed until no more gas is produced, capturing the gas in the syringe.

  5️⃣ Record Readings: Measure the volume of gas collected and note the mass of the solid reactant used.

  6️⃣ Calculate Molar Volume: Divide the volume of gas produced by the number of moles of the reactant used.

  7️⃣ Repeat: Conduct multiple trials and calculate the average molar volume.
• Why is the molar volume of an ideal gas approximately 22.4 dm³/mol at STP?

  Gas particles are far apart
• Match the equipment with its purpose in measuring molar volume:

  Round-bottom flask ↔️ Contains the reaction mixture

  Gas syringe ↔️ Measures gas volume

  Balance ↔️ Weighs reactants

  Measuring cylinder ↔️ Measures liquid volumes
• The formula to calculate molar volume is V_{m} = \frac{V}{n}
• What formula is used to calculate the number of moles (n) of a solid reactant?

  $n =$$\frac{m}{M}$
• 1 dm³ is equal to 1000 cm³.
• What is the molar mass of magnesium (Mg)?

  24.3 g/mol
• To calculate the number of moles of 2.4 g of magnesium, you divide the mass by its molar mass.
• Steps to calculate molar volume from data

  1️⃣ Calculate the number of moles (n) using the formula $n =$$\frac{m}{M}$.

  2️⃣ Divide the volume (V) by the number of moles (n) using the formula $V_{m} =$$\frac{V}{n}$.

  3️⃣ Convert units if needed, such as changing cm³ to dm³ by dividing by 1000.
• 1000 cm³ is equal to 1 dm³.
• What is the molar volume of hydrogen gas produced when 2.4 g of magnesium reacts to produce 1000 cm³ of gas?

  10.13 dm³/mol
• What are the units for molar volume?

  dm³/mol or cm³/mol
• In the formula for molar volume, $n$ represents the number of moles
• What is the formula to calculate the number of moles (n)?

  $n =$$\frac{m}{M}$
• Steps to calculate molar volume

  1️⃣ Calculate the number of moles (n)

  2️⃣ Divide the volume (V) by the number of moles (n)

  3️⃣ Convert units if needed
• 1 dm³ is equal to 1000 cm³
• In the example provided, what is the molar mass of magnesium (Mg)?

  24.3 g/mol
• In the example, the number of moles of Mg is approximately 0.0987
• What is the molar volume of hydrogen gas in the example?

  $10.13 \text{ dm}^{3} / \text{mol}$
• Temperature fluctuations can affect the volume of a gas
• What is the definition of molar volume of a gas?

  Volume per mole
• At standard temperature and pressure (STP), the molar volume of an ideal gas is approximately $22.4 \text{ dm}^{3} / \text{mol}$
• What is the purpose of a round-bottom flask in the experiment?

  Contains reaction mixture
• A balance is used to accurately weigh reactants in the experiment
• Which apparatus is used to collect and measure gas volume?

  Gas syringe
• The round-bottom flask should be mounted on a clamp
• What two tools are used to prepare reactants?

  Measuring cylinder and balance
• Steps to measure the molar volume of a gas

  1️⃣ Position Setup: Mount the round-bottom flask

  2️⃣ Prepare Reactants: Measure liquid volume and weigh solid reactant

  3️⃣ React Mix: Add liquid to flask, then solid reactant

  4️⃣ Collect Gas: Allow reaction to complete

  5️⃣ Record Readings: Measure gas volume and reactant mass

  6️⃣ Calculate Molar Volume: Use the formula

  7️⃣ Repeat: Conduct multiple trials and calculate the average
• The formula to calculate molar volume is V_{m} = \frac{V}{n}
• The apparatus for this experiment includes a gas syringe, clamp stand, and bung with a gas-tight seal.
• When gathering data, you should record the volume of gas collected and the mass of the solid reactant used in the following table
• Match the measurement with its corresponding unit.

  Volume of gas ↔️ $\text{dm}^{3}$ or $\text{cm}^{3}$

  Mass of solid reactant ↔️ $\text{g}$
• To calculate the number of moles, use the formula n = \frac{m}{M}
• 1 dm³ is equal to 1000 cm³.
• Gas leakage during the experiment can lead to an underestimation
• What is the molar volume of an ideal gas at STP?

  22.4 \text{ dm}^{3} / \text{mol}</latex>