Ca + Cl2 = CaCl2
m(CaCl2) = 69g
M(CaCl2) = 35.5 * 2 + 40 = 111 g/mol
n(CaCl2) = m/M = 69 / 111 = 0.6216
n(CaCl2) = n(Ca) = 0.6216
M(Ca) = 40 g/mol
m(Ca) = n*M = 40 * 0.6216 = 24.86 g
