TBR Gen Chem I - Equilibrium - Passage IV

[Monkeymaniac]

For anyone who used the TBR gen chem I book before, could anyone understsand the passage correctly?

The passage talks about a flask being filled with 1 atm of CS2 gas and glass cylinder that's connected to the flask that's filled with 1 atm of H2 gas, which are eventually allowed to mix together to reach an equilibrium. But then suddently, it talks about how the initial partial pressure of hydrogen gas is 0.8 atm in the closed system and that the total pressure of the system is 1 atm. WTF? 1 atm plus 1 atm is 2 atm right? Also shouldn't the initial partial pressure of H2 be 1 atm?

After looking at solutions, I realized that I should have somehow deduced that the initial total internal pressure is 1 atm and that the initial partial pressure of CS2 gas is 0.2 atm. Initially approaching the problems with the understanding that there are initially 1 atm of H2 gas and 1 atm of CS2 gas, of course, made me "incorrectly" answer some of the questions. Am I missing something here? Thanks in advance?

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[Monkeymaniac]

Anyone please?

 

[2010premed]

this exact point also confused me... I'd appreciate some help too on this 1

 

[dblue10]

Can anyone reconcile the contradiction between the passage and answer choices that the OP pointed out? (total of 2atm in the passage while answer to question 25 says 1atm total)

Thanks!

 

[dblue10]

Also this would be Section 3 (Equilibrium) of Book 1

 

[Temperature101]

For anyone who used the TBR gen chem I book before, could anyone understsand the passage correctly?

The passage talks about a flask being filled with 1 atm of CS2 gas and glass cylinder that's connected to the flask that's filled with 1 atm of H2 gas, which are eventually allowed to mix together to reach an equilibrium. But then suddently, it talks about how the initial partial pressure of hydrogen gas is 0.8 atm in the closed system and that the total pressure of the system is 1 atm. WTF? 1 atm plus 1 atm is 2 atm right? Also shouldn't the initial partial pressure of H2 be 1 atm?

After looking at solutions, I realized that I should have somehow deduced that the initial total internal pressure is 1 atm and that the initial partial pressure of CS2 gas is 0.2 atm. Initially approaching the problems with the understanding that there are initially 1 atm of H2 gas and 1 atm of CS2 gas, of course, made me "incorrectly" answer some of the questions. Am I missing something here? Thanks in advance?

That was a fu...hard passage. I manage to get 4 out of 7 questions right without understanding fully the passage...Hopefully someone here can explain this passage.

 

[MT Headed]

I don't have the book, and the question was not described very completely, but I'm guessing that a chamber of CS2 gas at 1atm and another chamber of H2 gas at 1atm were connected by a small hose or something. I'm also guessing that the H2 chamber was 4x the size of the CS2 chamber.

PV=nRT --> P=nRT/V
n, R, and T did not change

CS2: V is now 5x as big, so pressure of CS2 is 5x smaller
H2: V is now 5/4 as big, so pressure of H2 is 4/5 its original value

 

[dblue10]

I don't have the book, and the question was not described very completely, but I'm guessing that a chamber of CS2 gas at 1atm and another chamber of H2 gas at 1atm were connected by a small hose or something. I'm also guessing that the H2 chamber was 4x the size of the CS2 chamber.

PV=nRT --> P=nRT/V
n, R, and T did not change

CS2: V is now 5x as big, so pressure of CS2 is 5x smaller
H2: V is now 5/4 as big, so pressure of H2 is 4/5 its original value

Wow. I can't believe I overlooked that. Thanks for the help!

 

[DrDreams]

You know I still dont get this. Here are the facts.
A glass column of 1 liter, 3 flasks are attached with 250mL each. So the total volume of the system is 1.75L. The closed glass cylinder is filled with 1atm of hydrogen gas, and flask 1 is filled with 1atm of CS2. Reaction starts when the stopcock is opened, and the temperature is maintained. The total pressure of the system decreases. It says that the initial partial pressure of the gas is 0.8atm,in the 1.2L closed system. The decrease in partial pressure of the hydrogen gas is double the decrease in the internal pressure based on the stoichiometry.

How can the partial pressures of CH4 and H2S at equilibrium be determined from the experiment? I answered that the change in pressure is twice the value of the change in pressure of the system.