Question

Determine the percent composition of all elements in enstatite, MgSiO3, a mineral found in Earth's crust.

Answer 1

Magnesium:
Mg molar mass: 24.3050
You have one atom of Mg so, 24.211% (mass percent)

Silicon:
Si molar mass: 28.0855
You have one atom of Si so, 27.977% (mass percent)

Oxygen:
O molar mass: 15.9994
You have three atoms so, 47.812% (mass percent)

Answer 2

Explanation:

Percentage of an element in a compound:

$\frac{\text{Number of atoms of element}\times \text{Atomic mass of element}}{\text{molecular mass of compound}}\times 100$

Mass of magnesium atom = 24 g/mol

Mass of silicon atom = 28 g/mol

Mass of oxygen atom = 16 g/mol

Molar mass of $MgSiO_3$ =24 g/mol+28 g/mol+3 × 16 g/mol=100 g/mol

Composition of all elements in enstatite, $MgSiO_3$

Percentage of magnesium :

$\frac{1\times 24 g/mol}{100 g/mol}\times 100=24\%$

Percentage of silicon:

$\frac{1\times 28 g/mol}{100 g/mol}\times 100=28\%$

Percentage of oxygen:

$\frac{3\times 16 g/mol}{100 g/mol}\times 100=48\%$