posted by Robert on .
A sample of metallic element X, weighing 4.315g, combines with0.4810 L of Cl2 gas (at normal pressure and 20.0C) to form the metal chloride with the formula XCl. If the density of Cl2 gas under these conditions is 2.948g/L, what is the mass of chlorine? The amu of chlorine is 35.453. What is the atomic mass of X?
2X + Cl2 ==> 2XCl
mass X = 4.315g
L Cl2 = 0.4810; density = 2.948 g/L
mass Cl2 = 0.4810L x 2.948 g/L = 1.418g.
mols Cl = 1.418/35.453 = 0.0400 mols.
Since 0.0400 mols Cl reacted we know it must have done so with 0.0400 mols X.
mols = grams/atomic mass or
atomic mass = grams/mols
atomic mass X = 4.315/0.0400 = about 107 but you can finish.
Can you identify the metal X? Look at the atomic mass for Ag.