A volume of 0.155 L of a gas at STP weighs 0.412 g. Calculate the molar mass of the gas.
n = mols gas = 0.155/22.4 = ?
n = grams/molar mass. You know n and grams, solve for molar mass.
To calculate the molar mass of a gas, we need to use the ideal gas law equation:
PV = nRT
Where:
P = pressure (measured in atm)
V = volume (measured in liters)
n = number of moles
R = ideal gas constant (0.0821 L·atm/mol·K)
T = temperature (measured in Kelvin)
In this case, the gas is at STP (standard temperature and pressure), which means the pressure is 1 atm and the temperature is 273 K.
First, let's calculate the number of moles (n) using the ideal gas law equation:
PV = nRT
1 atm * 0.155 L = n * (0.0821 L·atm/mol·K) * 273 K
0.155 atm·L = 22.42 n
n = 0.155 atm·L / 22.42 = 0.00691 mol
Next, let's calculate the molar mass (M) using the mass of the gas and the number of moles:
M = mass / moles
M = 0.412 g / 0.00691 mol
M = 59.63 g/mol
Therefore, the molar mass of the gas is 59.63 g/mol.