An oxide is known to have the formula M207 and to contain 76

An oxide is known to have the formula M207, and to contain 76.9% M by mass.

What is the atomic mass of M?

Solution

Suppose the MW of the metal is x

Then 2*x /(2x+7*16) = 0.769

=> 2*x /2*x +112 = 0.769

=> 2*x = 86.128+1.53*x

=> 0.47x = 86.128

=> x = 183.25

Hence the MW of the M is 183.25