3.5 Use of amount of substance in relation to volumes of gases

• One mole contains approximately 6.022 x 10²³ entities, a value known as Avogadro's number.
• Avogadro's Law implies that the volume of a gas is directly proportional to the number of moles it contains.
• At STP, one mole of any gas occupies a volume of 22.4 liters.
• To convert moles to volume at STP, multiply the number of moles by 22.4 liters per mole.
• One mole contains 6.022 x 10²³ entities.


  True
• The volume of a gas is directly proportional to the number of moles it contains according to Avogadro's Law.


  True
• What volume does one mole of any gas occupy at STP?

  22.4 liters
• To convert the volume of a gas at STP to the number of moles, use the formula: Number of moles = Volume / Molar volume at STP
• Steps for gas volume calculations using balanced chemical equations

  1️⃣ Balance the chemical equation

  2️⃣ Determine the mole ratio

  3️⃣ Calculate the volume using molar volume at STP
• Steps for gas volume calculations using balanced chemical equations

  1️⃣ Balance the chemical equation

  2️⃣ Determine the mole ratio

  3️⃣ Calculate the volume
• If 2 moles of nitrogen gas react, what volume of ammonia will be produced at STP?

  89.6 liters
• The volume of a gas is directly proportional to the number of moles it contains according to Avogadro's Law


  True
• The molar volume at STP is 22.4 liters per mole


  True
• What is the molar volume of a gas at STP?

  22.4 liters
• Match the concept with its definition:

  Molar Volume ↔️ Volume occupied by one mole

  STP ↔️ Standard Temperature and Pressure
• The molar volume at STP is 22.4 liters per mole.
• What is the molar volume at STP?

  22.4 L/mol
• Match the reaction with its gas volumes at STP:

  N₂ ↔️ 22.4 L

  H₂ ↔️ 67.2 L

  NH₃ ↔️ 44.8 L
• 2 moles of nitrogen gas produce 89.6 liters of ammonia at STP.


  True
• What is the SI unit for measuring the amount of a substance?

  Mole
• If 2 moles of a gas occupy a certain volume, what volume will 1 mole of the same gas occupy under identical conditions?

  Half the volume
• What is the molar volume of a gas at STP in liters?

  22.4
• The molar volume at STP is 22.4 liters per mole.


  True
• What is the SI unit for measuring the amount of a substance?

  Mole
• What is Avogadro's number?

  6.022 x 10²³
• What volume does 3 moles of hydrogen gas occupy at STP?

  67.2 liters
• Balancing chemical equations is the first step in gas volume calculations using stoichiometry.

  True
• A gas sample with a volume of 44.8 liters at STP contains 2 moles of the gas.
• Match the reaction with its mole ratio and gas volumes at STP:

  N₂ + 3H₂ → 2NH₃ ↔️ 1:3:2

  N₂: Gas volume at STP ↔️ 22.4 L

  H₂: Gas volume at STP ↔️ 67.2 L
• What does Avogadro's Law state about equal volumes of gases at the same temperature and pressure?

  Equal number of molecules
• How many moles are present in 44.8 liters of gas at STP?

  2 moles
• At STP, one mole of any gas occupies a volume of 22.4 liters.
• One mole of any gas occupies 22.4 liters at STP.

  True
• Steps to convert moles to volume of gas at STP:

  1️⃣ Multiply the number of moles by the molar volume at STP (22.4 L/mol)
• To convert the volume of a gas at STP to the number of moles, divide the volume by 22.4 L/mol.
• Steps for gas volume calculations using balanced chemical equations:

  1️⃣ Balance the chemical equation

  2️⃣ Determine the mole ratio

  3️⃣ Calculate the volume using molar volume at STP
• What is the mole ratio of N₂ to NH₃ in the balanced equation N₂ + 3H₂ → 2NH₃?

  1:2
• Avogadro's Law states that equal volumes of different gases contain equal numbers of molecules at the same temperature and pressure.


  True
• Standard Temperature and Pressure (STP) is defined as 0°C and 1 atmosphere.


  True
• If 2 moles of oxygen gas are at STP, what volume do they occupy?

  44.8 liters