Calculation of the Atomic Mass of the Metal

Given:
Mass of chlorine (Cl) = 71 g
Mass of chloride (MgCl2.6H2O) = 111 g

To find the atomic mass of the metal, we need to consider the molar ratio between the metal and chlorine in the chloride compound.

1. Determining the Moles of Chlorine:
Using the molar mass of chlorine (Cl = 35.5 g/mol), we can calculate the moles of chlorine in the given mass:

Moles of Cl = Mass of Cl / Molar mass of Cl
= 71 g / 35.5 g/mol
= 2 moles

2. Determining the Moles of Chloride:
The molar mass of the chloride compound can be calculated by considering the molar masses of magnesium (Mg), chlorine (Cl), and water (H2O).

Molar mass of MgCl2.6H2O = Molar mass of Mg + 2 × Molar mass of Cl + 6 × Molar mass of H2O

Molar mass of MgCl2.6H2O = (24.3 g/mol) + 2 × (35.5 g/mol) + 6 × [(1 g/mol) + (16 g/mol)]
= 24.3 g/mol + 2 × 35.5 g/mol + 6 × 18 g/mol
= 24.3 g/mol + 71 g/mol + 108 g/mol
= 203.3 g/mol

Now, we can calculate the moles of chloride:

Moles of chloride = Mass of chloride / Molar mass of chloride
= 111 g / 203.3 g/mol
= 0.545 moles

3. Determining the Moles of Metal:
Since the chloride compound has a 1:1 molar ratio between the metal and chlorine, the moles of the metal will also be 0.545 moles.

4. Calculating the Atomic Mass of the Metal:
The atomic mass of the metal can be calculated using the equation:

Atomic mass of metal = Mass of metal / Moles of metal

Since we already know the moles of the metal (0.545 moles), we can rearrange the equation to solve for the mass of the metal:

Mass of metal = Atomic mass of metal × Moles of metal
= Atomic mass of metal × 0.545 moles

Substituting the known values:
111 g = Atomic mass of metal × 0.545 moles

Solving for the atomic mass of the metal:
Atomic mass of metal = 111 g / 0.545 moles
≈ 203.67 g/mol

Therefore, the atomic mass of the metal is approximately 203.67 g/mol.