Starter quiz
- Which unit is most commonly used to measure the volume of a gas?
- L
- ml
- cm³ ✓
- dm³
- m³
-
- What is the molar gas volume of any gas at room temperature and pressure (20°C and 1 atmosphere)?
- 12 dm³
- 18 dm³
- 24 dm³ ✓
- 36 dm³
-
- Molar gas volume is the volume occupied by ______ of any gas at room temperature and pressure, standardised at 24 dm³ or 24 000 cm³.
- 'one mole' ✓
- Which equation would you use to calculate the number of moles from the volume of a gas?
- moles = mass ÷ molar mass
- moles = volume ÷ molar volume ✓
- moles = density × volume
- moles = concentration × volume
-
- True or false? The number of moles of a gas can only be calculated if you know the volume of the gas and the conditions of temperature and pressure.
- True ✓
- False
- Calculate the volume of 0.5 moles of nitrogen gas at room temperature and pressure. Assume the molar gas volume is 24 dm³ per mole. Give your answer to 2 s.f. Volume of nitrogen gas = ______ dm³.
- '12' ✓
Exit quiz
- When converting the volume of a gas to the mass of a solid reactant in a balanced reaction, what must you first determine?
- the density of the gas
- the relative mass of the solid
- the number of moles of gas ✓
- the temperature of the gas
-
- Order the following steps to calculate the mass of a solid reactant from the volume of a gas product in a chemical reaction. Starting with the volume of gas.
- 1⇔Determine the volume of the gas.
- 2⇔Calculate the number of moles of gas from its volume.
- 3⇔Use the stoichiometry of the balanced equation to find the moles of reactant.
- 4⇔Calculate the mass of the reactant using its relative mass.
- If 24 dm³ of hydrogen gas react with oxygen to form water, how many moles of oxygen gas were used? 2H₂ + O₂ → 2H₂O.
- 1 mole
- 2 moles
- 0.5 moles ✓
- 1.5 moles
-
- A sample of oxygen gas weighing 16 g is used in a reaction. Calculate the volume it occupies at room temperature and pressure. The RFM of oxygen (O₂) is 32.0. The molar gas volume is 24 dm³.
- 12 dm³ ✓
- 24 dm³
- 36 dm³
- 384 dm³
- 0.67 dm³
-
- Calculate the volume of CO₂ gas produced when 100 g of CaCO₃ decomposes. CaCO₃ → CaO + CO₂. Assume all of the CaCO₃ reacts, the molar gas volume is 24 dm³. RFM CaCO₃ = 100.1, CaO = 56.1, CO₂ = 44.0
- 12 dm³
- 24 dm³ ✓
- 48 dm³
- 43 dm³
- 13 dm³
-
- Given 500 cm³ of oxygen gas at RTP, calculate the mass of H₂ gas that completely reacts with it to form water. Give answer to 2 s.f. 2H₂ + O₂ → 2H₂O. The molar gas volume is 24 dm³. RFM of H₂ = 2.0
- '0.083 g' ✓
Worksheet
Presentation
Video
Lesson Details
Key learning points
- The volume of one mole of any gas at room temperature and pressure (20℃ and 1 atmosphere pressure) is 24 dm³.
- Reacting mass calculations can use a combination of mass to volume calculations and vice versa.
- Amount of substance (moles) can be calculated using multiple equations.
- The choice of equation for calculating moles depends on the context of the problem or calculation.
Common misconception
Pupils use an incorrect mathematical relationship to calculate the number of moles in a sample.
Depending on the type of substance (solid, solution or gas) a specific mathematical relationship for moles must be used. Challenge pupils to classify substances as (s), (aq), or (g) and apply correct mathematical relationship.
Keywords
Mole - A mole of something is 6.02 × 10²³ of it. The mass of a mole of a substance is its relative mass expressed in grams.
Volume - Volume is how much 3D space matter occupies. It is usually measured in cm³.
Molar gas volume - Molar gas volume is the volume occupied by one mole of any gas. It is equal to 24 dm³ or 24 000 cm³ at room temperature and pressure.
Stoichiometry - Stoichiometry refers to the molar ratio of the reactants and products in a chemical reaction.
Balanced symbol equation - A balanced symbol equation describes a reaction using a symbol equation with coefficients, which ensure there are equal numbers of atoms of each element on both sides of the symbol equation.