Answer:
48 g/mol
Explanation:
Step 1: Calculate the mass of the gas (m)
According to the law of conservation of mass, the mass of the solid before the decomposition must be equal to the sum of the masses of the solid residue and the gas
mSolid = mResidue + mGas
mGas = mSolid - mResidue = 4.73 g - 4.10 g = 0.63 g
Step 2: Convert 320 cm³ to L
We will use the conversion factor 1 L = 1000 cm³.
320 cm³ × 1 L/1000 cm³ = 0.320 L
Step 3: Calculate the moles of gas (n)
The gas is at room temperature (298.15 K) and room pressure (1 atm). We can calculate the moles of gas using the ideal gas equation.
P × V = n × R × T
n = P × V/R × T
n = 1 atm × 0.320 L/(0.0821 atm.L/mol.K) × 298.15 K = 0.0131 mol
Step 4: Calculate the molecular mass of the gas (M)
We will use the following expression.
M = m/n = 0.63 g/0.0131 mol = 48 g/mol
