Question- Determine the empirical and molecular formula for chrysotile asbestos. Chrysotile has the following percent composition: 28.03% Mg, 21.60% Si, 1.16% H, and 49.21% O. The molar mass for chrysotile is 520.8g/mol.

Percent composition of Mg-28.03%

Percent composition of Si- 21,60%

Percent composition of H- 1.16%

Percent composition of O-49.21%

The molar mass of Mg = 24g

The molar mass of Si = 28g

The molar mass of H = 1g

The molar mass of oxygen = 16g

Moles of Mg = 28.03/24 = 1.167mol

Moles of Si = 21.60/28 = 0.77mol

Moles of H = 1.16/1 = 1.16mol

Moles of O = 49.21/16 = 3.07mol

Dividing moles by the smallest number i.e 0.77

Moles of Mg = 1.5 mol

Moles of Si = 1mol

Moles of H = 1.5mol

Moles of O = 3.9

Now, the empirical formula will be

Mg_1.5Si₁H_1.5O_3.9

Multiplying by 2 to make it a whole number

= Mg₃Si₂H₃O₈

The molecular mass of the empirical formula

= (3 x 24) +( 2 x 28 )+ (3 x 1) +( 8 x 16)

= 259g

Given mass = 520.8g

N = given mass/empirical formula mass

= 520.8g/259g = 2

Now multiplying n to the empirical formula to get the molecular formula

Therefore, the molecular formula = Mg₆Si₄H₆O₁₆