# In the first step of silicon purification, a reaction is brought about between the impure silicon and chlorine.

Hi Could someone please check my calculations for the question below:

2. In the first step of silicon purification, a reaction is brought about between the impure silicon and chlorine. Pure silicon is then used, in the computer industry, for the manufacture of microchips.

Si + Cl2 = SiCl4 (unbalanced equation)

Si + 2Cl2 = SiCl2

1 mol 2 mol 1 mol

Given that the silicon is 92% pure, calculate the theoretical yield percentage if 1.0 t of impure silicon produces 2.33 t of silicon (IV) chloride.                            (6 marks)

Molar Mass of SiCl4 = (28.9 +4 x 35.45) = 169.90 g/mol

Molar Mass of Si = (28.09) g/mol

Moles of SiCl4 = 1.0 x 10^6 g

169.90 g/mol

= 0.005885 x 10^6 mol or 5.885 x 10^3 mol

Number of moles of Si = 5.885 x 10^3 mol x1   = 5.885 x 10^3mol

1

Mass of Si = 5.885 x 10^3 mol x 28.09 g/mol = 165.309 x 10^3 g

= 1.65309 x 10^5 g

Yield% for Si = 2.3 x 10^6 g / 1.65309 x 10^5 g

= 3.80210 x 10^1 x 100 / 92 or 4%