If the compound contains 35.06 % cl by mass, what is the identity of the metal?

Answer is: identity of the metal is gold (Au).

ω (Cl) = 35.06% : 100%.

ω (Cl) = 0.3506; mass percentage of chlorine.

If we take 100 grams of the compound:

m (Cl) = ω (Cl) · m (compound).

ω (Cl) = 0.3506 · 100 g.

ω (Cl) = 35.06 g.

n (Cl) = m (Cl) : M (Cl).

n (Cl) = 35.06 g : 35.45 g/mol.

n (Cl) = 0.99 mol; amount of substance.

In molecule MCl₃: n (M) : n (Cl) = 1 : 3.

n (M) = 0.33 mol; amount of unknown metal.

M (M) = m (M) : n (M).

M (M) = (100 g - 35.06 g) : 0.33 mol.

M (M) = 196.8 g/mol; molar mass of the gold.