To determine the molar mass of a gas, we can use either the molar volume at standard temperature and pressure (STP) or the ideal gas law equation.
A: To find the molar mass of a gas given its mass and volume at STP, we can use the molar volume at STP, which is equal to 22.4 L/mol.
1. Convert the given volume from liters to moles:
1.50 L × (1 mol / 22.4 L) = 0.067 mol
2. Calculate the molar mass by dividing the mass (in grams) of the gas by the number of moles:
Molar mass = 11.2 g / 0.067 mol ≈ 166.27 g/mol
Therefore, the molar mass of the gas in scenario A is approximately 166.27 g/mol.
B: To determine the molar mass of a gas given its mass and volume, we can use the ideal gas law equation, which is PV = nRT.
1. Convert the given volume from milliliters to liters:
825 mL × (1 L / 1000 mL) = 0.825 L
2. Convert the given mass from grams to moles using the molar mass:
Molar mass = 0.0710 g / (0.825 L × 1 atm / (0.0821 L·atm/(mol·K)) × 273.15 K) = 1.88 g/mol
Therefore, the molar mass of the gas in scenario B is approximately 1.88 g/mol.