Question

What percent of magnesium bromide, MgBr2, is magnesium?

Answer 1

The percent of magnesium in magnesium bromide (MgBr2) is approximately 13.28%, calculated using the molar masses of magnesium and magnesium bromide and their proportion in the compound.

Step-by-step explanation:

To calculate the percent of magnesium in magnesium bromide (MgBr2), we first need the molar masses of magnesium and magnesium bromide. Magnesium has a molar mass of about 24.31 g/mol, and bromine has a molar mass of about 79.904 g/mol. Since there are two bromine atoms in magnesium bromide, the molar mass of MgBr2 is 24.31 g/mol (Mg) + 2 × 79.904 g/mol (Br) = 183.118 g/mol.

To find the percent composition of magnesium in MgBr2, we use the formula:

Percent by mass = (molar mass of Mg / molar mass of MgBr2) × 100%

Plugging the values in, we get:

Percent by mass = (24.31 g/mol / 183.118 g/mol) × 100% ≈ 13.28%

Therefore, magnesium constitutes approximately 13.28% of magnesium bromide by mass.

Answer 2

first, we need to calculate the molar mass of the whole compound by adding the masses of each atom from the periodic table.

Mg= 24.3 g/mol
Br= 80.0 g/mol

molar mass MgBr2= 24.3 + 2 x 80.0= 184.3 g/mol

to find the percent of magnesium doing "parts over the whole"
the mass of magnesium over the total mass. then times 100 because it is a percentage value

24.3/184.3x 100= 13.2%