Question

Determining the empirical and molecular formula for chyrsotile asbestos. Chyrsotile has the following percent composition:

28.03% Mg, 21.60% Si, 1.16% H and 49.21% O. The molar mass of chyrsotile is 520.8 g/mol.

Answer 1

The molecular formula of chyrsotile asbestos :
`Mg_6Si_4H_6O_(16)`

The empirical formula for chyrsotile asbestos :
`Mg_3Si_2H_3O_(8)`

Step-by-step explanation:

The molar mass of chyrsotile = M= 520.8 g/mol.

Let the molecular formula of chyrsotile be
`Mg_wSi_xH_yO_z`

Percentage of Mg = 28.03%

Percentage of Si =21.60%

Percentage of H=1.16%

Percentage of O = 49.21%

Percentage of an element in a compound:

`\frac{\text{Number of atoms of element}* \text{Atomic mass of element}}{\text{molecular mass of element}}* 100`

1) Magnesium atom with mass 24 g/mol.

`28.03\%=(w* 24 g/mol)/(520.8 g/mol)* 100`

w = 6.0

2) Silicon atom with mass 28 g/mol.

`21.60\%=(x* 28 g/mol)/(520.8 g/mol)* 100`

x = 4.0

3) Hydrogen atom with mass 1 g/mol.

`1.16\%=(y* 1 g/mol)/(520.8 g/mol)* 100`

y = 6.0

4) Oxygen atom with mass 28 g/mol.

`49.21\%=(z* 16 g/mol)/(520.8 g/mol)* 100`

z = 16.0

The molecular formula of chyrsotile asbestos :
`Mg_6Si_4H_6O_(16)`

Empirical is the lowest ratio of numbers of different atoms present in a compound.

The empirical formula for chyrsotile asbestos :
`Mg_3Si_2H_3O_(8)`