What is the mass of bromine in 11.2g of MgBr2?

9.72 grams of Br

Explanation:

This is the salt: MgBr₂ (Magnesium bromide)

1 mol of MgBr₂ has 1 mol of Mg and 2 mol of Br

Molar mass MgBr₂ → 184.11 g/m

So the rule of three will be:

184.11 g of salt have 2 moles of Br

11.2 g of salt have (11.2. 2) / 184.11 = 0.122 moles of Br.

Molar mass Br = 79.9 g/m

Mol. molar mass = mass → 0.122 m. 79.9 g/m = 9.72 g