At standard temperature and pressure (STP), which is defined as 0 degrees Celsius (273.15 Kelvin) and 1 atmosphere (atm) of pressure, one mole of any ideal gas occupies 22.4 liters.
To calculate the volume of a specific amount of gas, such as 11.5 grams of O₂, you need to convert the mass of the gas into moles using the molar mass of oxygen (O₂), which is 32 g/mol. The molar mass represents the mass of one mole of a substance.
First, calculate the number of moles of O₂:
moles = mass / molar mass moles = 11.5 g / 32 g/mol moles ≈ 0.359 moles
Next, use the ideal gas law, which states PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant (0.0821 L·atm/(mol·K)), and T is the temperature in Kelvin.
At STP, the pressure is 1 atm, so the equation becomes:
V = (nRT) / P V = (0.359 mol * 0.0821 L·atm/(mol·K) * 273.15 K) / 1 atm V ≈ 8.742 liters
Therefore, a 11.5 g sample of O₂ at STP would occupy approximately 8.742 liters.