In the direct reaction of silicon with Cl2 the yield of SiCl4 is 50. %. How many grams of silicon must be reacted with excess chlorine in order to obtain 17 g SiCl4

5.6 g

Explanation:

The computation of the number of grams of silicon is shown below:

But before that we dop the following calculations

Given that

actual yield = 17 g

Now

Percentage of yield = actual yield × 100 ÷ theoretical yield

50 = 17 g × 100 ÷ theoretical yield

So,

theoretical yield = 34 g

Now

The Molar mass of SiCl_4,

MM = 1 × MM(Si) + 4 × MM(Cl)

= 1 × 28.09 + 4 × 35.45

= 169.89 g/mol

And,  

mass of SiCl_4 = 34 g

Also,

mol of SiCl_4 = (mass) ÷ (molar mass)

= 34 ÷ 1.699*10^2

= 0.2001 mol

The Balanced chemical equation is:

S_i + 2 Cl_2 —> SiCl_4

As per the balanced equation

mol of Si formed = moles of SiCl_4

= 0.2001 mol

Molar mass of Si = 28.09 g/mol

mass of Si = number of mol × molar mass

= 0.2001 × 28.09

= 5.6 g