Calculate the theoretical yield percentage for this reaction

[Kiah Palmer]

Homework Statement

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)

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.

Relevant Equations

(Balanced Equation) Si + 2Cl2 -> SiCl4

Conversion: 1.0 t = 1.0x10^6 g impure Si
Conversion: 2.33 t = 2.33x10^6 g SiCl4
Atomic Mass Si = 28.085 g/mol
Atomic Mass Cl2 = (2 x 35.453) = 70.906 g/mol
Mass SiCl4 = 28.085 + (4x35.453) = 169.897 g/molI got all this part down, however, I'm not quite sure where I am supposed to go from there...

 

[Borek]

How much silicon is there in 1.0 t of the starting material? How much SiCl₄ would you expect to make from it?

 

[Kiah Palmer]

so for that, I would need to find Mol Si and mol SiCl4, which I believe is as follows:

Theoretical # mol Si = 1.0x10^6 g / 28.085 g/mol = 3.6x10^4 mol

Theoretical # Mol SiCl4 = 2.33x10^6 g / 169.897 g/mol = 1.4x10^4 mol

I think this would be correct for the # mol (if that was even needed) But I am still a bit confused as to what I would do next. Is this where the equation to find the theoretical yield percentage would go?? Or is there steps in between missing still?

 

[Borek]

Theoretical # mol Si = 1.0x10^6 g / 28.085 g/mol = 3.6x10^4 mol

No. You don't have a ton of Si. You have a ton of a material which contains 92% Si.

 

[Kiah Palmer]

No. You don't have a ton of Si. You have a ton of a material which contains 92% Si.

Ok, so then I would need to use Mol SiCl4 then calculate the yield percent? Or do I need to find out what 92% of the mass of Si would be first, then recalculate mol?

 

[Borek]

See my first post in the thread, it addresses exactly questions you are asking now.