What percentage of the total atomic mass of magnesium bromide (MgBr2) is composed of bromine? Hint - consider the mass of both atoms of bromine in your calculation. A.43% B.87% C.13% D.63%

B. 87%

Explanation:

First, we calculate the molecular mass of magnesium bromide (MgBr2) as follows;

MgBr2 = 24.3 + 79.9(2)

= 184.1g/mol

Since 1 atom of bromine contains 79.9g, then the mass of two atoms of bromine (Br2) is 79.9 × 2 = 159.8g

Hence, the percentage of bromine (Br2) in MgBr2 is calculated as follows:

% mass of Br2 = mass of Br2/ molecular mass of MgBr2 × 100

% mass of bromine = 159.8/184.1 × 100

% mass of bromine = 0.8680 × 100

% mass of bromine = 86.8%

Approximately, % mass of bromine is 87%