1. Understand STP (Standard Temperature and Pressure)
* Temperature: 0°C (273.15 K)
* Pressure: 1 atm (101.325 kPa)
2. Use the Ideal Gas Law
The ideal gas law relates pressure (P), volume (V), number of moles (n), the ideal gas constant (R), and temperature (T):
PV = nRT
3. Determine the Number of Moles (n)
* Molar mass of helium (He): 4.0026 g/mol
* Number of moles (n) = mass (m) / molar mass (M)
* n = 84.6 g / 4.0026 g/mol = 21.14 mol
4. Choose the Appropriate Gas Constant (R)
* R = 0.0821 L·atm/mol·K (This value works when pressure is in atm and volume is in liters)
5. Solve for Volume (V)
* V = (nRT) / P
* V = (21.14 mol * 0.0821 L·atm/mol·K * 273.15 K) / 1 atm
* V ≈ 471.7 liters
Therefore, the volume of 84.6 grams of helium at STP is approximately 471.7 liters.
