# Chemical Forums

## Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: emilie on June 10, 2021, 08:43:47 PM

Title: Gases and stoichiometry question
Post by: emilie on June 10, 2021, 08:43:47 PM
Hi, I've been working on this chemistry problem for class and I'm not seeing where I'm messing up.

Here's the question:

Chlorine gas reacts with fluorine gas to form chlorine trifluoride.

Cl2(g) + 3 Fs(g)  :rarrow: 2 ClF3(g)

A 2.00-L reaction vessel, initially at 298 K, contains chlorine gas at a partial pressure of 337 mmHg and fluorine gas at a partial pressure of 729 mmHg. Identify the limiting reactant and determine the theoretical yield of ClF3 in grams.

Here's what I did:

mol Cl2: PV = nRT

n = PV/RT = (337 mmHg x (1 atm / 760 mmHg) x 2.00 L) / (0.08206 L atm / mol K x 298K) = 0.036266 mol Cl2

mol F2: n = PV/RT = (729 mmHg x (1 atm / 760 mmHg) x 2.00 L) / (0.08206 L atm / mol K x 298 K) = 0.078451 mol F2

Limiting reactant

0.036266 mol Cl2 (3 mol F2 / 1 mol Cl2) = 0.109 mol F2

Limiting reactant is F2 since it's less than the Cl2

Theoretical yield of ClF3

0.078451 mol F2 (2 mol ClF3/3 mol F2)(92.45 g ClF3 / 1 mol F2) = 4.84 g ClF3

And this answer is not correct. What am I not seeing? Thanks!
Title: Re: Gases and stoichiometry question
Post by: emilie on June 10, 2021, 09:42:45 PM
Book answer is F2 is limiting reactant and  2.84 g ClF3 is the theoretical yield.
Title: Re: Gases and stoichiometry question
Post by: Borek on June 11, 2021, 02:43:49 AM
Your answer looks OK to me, must be an error in the book.