Calculating Mass in a Gas Stoichiometry Problem

[Lili123]

Hi all,
While studying for my exam (and doing review questions) I came across a problem that I couldn't solve:

5. Zirconium metal and chlorine gas react to form zirconium (IV) chloride
Zr + 2Cl2 = ZrCl4
a) What volume of chlorine gas must be used at 350 degrees Celsius and 50 kPa to produce 200mL of ZrCl4 under the same conditions?

Figured out this part, and it comes to 400mL of chlorine gas.

b) What mass of zirconium will be used up?This part I had trouble on. I used the moles of chlorine gas to do this, though it feels like I'm doing something wrong, could someone let me know if what I am doing is right? We don't have an answer key... Thanks in advance!

0.003860124 mols Cl2 * 1 mol Zr / 2 mols Cl2 * 91.224g/mol Zr = 0.176 g Zr

 

[Borek]

0.003860124 mols Cl2

Why 0.00386 moles of Cl₂?

 

[Lili123]

Why 0.00386 moles of Cl₂?

Because in part A of the question I determined the moles of ZrCl4 using this formula: n = PV / RT and then used the mole ratio to convert to Cl2.
n = (50) (0.200) / (8.3145) (623.15) * 2mols Cl2 / 1mol ZrCl4 = 0.003860124

 

[Borek]

Oops, you are right. I used a wrong volume in my calculations.

0.176 g of Zr is a correct answer.