A binary compound created by reaction of bismuth and an unknown element E contains 52.07% Bi and 47.93% E by mass. If the formula of the compound is Bi2E3, calculate the atomic mass of E.

Atomic mass of E is 128.24

Explanation:

The percentage composition by mass of an element in a compound is given by dividing the mass of the element by the total mass of the compound and expressing it as a percentage. In this case; the compound Bi₂E₃

Percentage composition of bismuth = 52.07%

Percentage composition of E = 47.93%

Mass Bismuth in the compound is (2*208.9804) = 417.96 g

Therefore,

To calculate the atomic mass of E

52.07% = 417.96 g

47.93% = ?

= (47.93 * 417.96) : 52.07 %

= 384.729

E₃ = 384.729

Therefore; E = 384.729 : 3

= 128.24

The atomic mass of E is 128.24