Answer:
The balanced chemical equation for the reaction between aluminum and chlorine gas is:
2Al + 3Cl2 → 2AlCl3
This equation tells us that 2 moles of aluminum will react with 3 moles of chlorine to form 2 moles of aluminum chloride.
Therefore, to react completely with 1.2 moles of aluminum, we need:
3/2 x 1.2 = 1.8 moles of Cl2
Now, we can use the relationship between moles and mass:
mass = moles x molar mass
The molar mass of Cl2 is 70.90 g/mol.
mass of Cl2 = 1.8 mol x 70.90 g/mol = 127.62 g
Therefore, to react completely with 1.2 moles of aluminum, we need 127.62 g of chlorine gas.