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Topic: Gas Law Problem: Dalton's Law and Kinetic Theory  (Read 6614 times)

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Offline teqniq

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Gas Law Problem: Dalton's Law and Kinetic Theory
« on: September 07, 2009, 11:28:08 AM »
I need some help with these two problems, I can't figure out what to do.

1)When acetylene, c2h2, is burned in oxygen, carbon dioxide and steam are formed. A sample of acetylene with a volume of 7.50 L and a pressure of 1.00 atm is burned in excess oxygen at 225C. The products are transferred without loss to a 10.0L flask at the same temperature.

a) Write the balanced equation for the reaction.
b) What is the total pressure of the products in the 10.0-L flask?
c) What is the partial pressure of each of the products in the flask?

I got the answer to a) (C2H2+ SO2= 4CO2 +2H2O), but I have no idea what to do for b) and c)?

The second problem is:

2)If 0.0129 mol of N2O4 effuses through a pinhole in a certain amount of time, how much NO would effuse in that same amount of time under the same conditions?

I attempted to solve it using Graham's Law, but that only works for the rate and the Molar Mass, and not the mols as is asked in the question.
Thanks!

Offline Yggdrasil

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Re: Gas Law Problem: Dalton's Law and Kinetic Theory
« Reply #1 on: September 07, 2009, 10:37:59 PM »
I need some help with these two problems, I can't figure out what to do.

1)When acetylene, c2h2, is burned in oxygen, carbon dioxide and steam are formed. A sample of acetylene with a volume of 7.50 L and a pressure of 1.00 atm is burned in excess oxygen at 225C. The products are transferred without loss to a 10.0L flask at the same temperature.

a) Write the balanced equation for the reaction.
b) What is the total pressure of the products in the 10.0-L flask?
c) What is the partial pressure of each of the products in the flask?

I got the answer to a) (C2H2+ SO2= 4CO2 +2H2O), but I have no idea what to do for b) and c)?

I assume you mean that O2 is a reactant, not SO2, and I'll also point out that the equation is not balanced (for example, there are four carbons on the product side but only two carbons on the product side).

For parts b and c, you'll need to use the ideal gas law.  For example, you would first need to find the number of moles of acetylene (n) in a volume of 7.5L at 1.0 atm and 225oC.

Quote
The second problem is:

2)If 0.0129 mol of N2O4 effuses through a pinhole in a certain amount of time, how much NO would effuse in that same amount of time under the same conditions?

I attempted to solve it using Graham's Law, but that only works for the rate and the Molar Mass, and not the mols as is asked in the question.
Thanks!

You're going in the right direction with Graham's Law.  Here's perhaps a question to guide you in the correct direction:  if NO were to effuse 2x faster than N2O4 (this number is made up and used only for illustrative purposes), what amount of NO would have effused through the hole in the same amount of time that it took 0.0129 moles of N2O4 to effuse out?

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