ideal gas law

Write down the ideal gas equation and explain what each symbol represents.

• Equation: pV=nRTpV = nRTpV=nRT

• p = pressure (Pa), V = volume (m³), n = number of moles (mol), R = gas constant (8.314 J mol⁻¹ K⁻¹), T = temperature (K)

• ✅ Each symbol must be correctly defined.

How do you calculate the number of moles of a gas using the ideal gas law?

n=pV/RT

• Convert all quantities to SI units first (Pa, m³, K).

• p in Pa (kPa × 1000), V in m³ (1 dm³ = 1 × 10⁻³ m³), T in K (°C + 273).

How can you link the density of a gas to its mass?

m=density×V

• Density is usually in g dm⁻³; volume in dm³.

• If needed, convert mass to kg for SI units.

What is the formula to calculate relative molecular mass from mass and moles?

M=m/n

• m = mass of the gas, n = number of moles.

• Ensure mass and moles are in consistent units (kg and mol).

How do you combine the formulas to calculate the molar mass directly from density?

M=mRT/pV

• Step 1: Convert all quantities to SI units.

• Step 2: Use density to find mass in 1 dm³.

• Step 3: Use n = pV / RT.

• Step 4: Divide mass by moles to get M.

Which steps would you follow in an exam to find the relative molecular mass from density?

1. Convert pressure, volume, temperature, and mass to SI units.

2. Calculate moles using n=pV/RT

3. Find mass of 1 dm³ from density.

4. Calculate molar mass: M=m/n​.

5. State the answer as Relative Molecular Mass (Mr).