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Author Topic: Gas  (Read 1328 times)

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Ter

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Gas
« on: December 18, 2012, 03:54:29 AM »

Hi I really am confused, will appreciate the *delete me*
From the modern Version of Gay-Lussac experiments, syringe A contains 50cm3 of nitrogen monoxide and syringe B contains 50cm3 of oxygen. In the experiment, 5.0cm3 portions of oxygen were pushed form syringe B to A. After each addition, the tap was closed. After the gases had returned to their original temperature, the total volume of gases remaining was measured.

Attached is the graph.


So, my question was:
Deduce the volume of nitrogen dioxide formed.

I know the oxygen is in excess and thus 25cm3 of oxygen reacted with 50cm3 of nitrogen monoxide, to form 75cm3 of nitrogen dioxide. It adds up to me, I wrote 75cm3. However, the answer was 50cm3, they took the total volume formed - 25cm3 of oxygen, I don't understand why. Dont they react with each other, 50cm3 of NO and 25cm3 of O2?

Please help,
thank you so much!
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sjb

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Re: Gas
« Reply #1 on: December 18, 2012, 04:11:37 AM »

Hi I really am confused, will appreciate the *delete me*
From the modern Version of Gay-Lussac experiments, syringe A contains 50cm3 of nitrogen monoxide and syringe B contains 50cm3 of oxygen. In the experiment, 5.0cm3 portions of oxygen were pushed form syringe B to A. After each addition, the tap was closed. After the gases had returned to their original temperature, the total volume of gases remaining was measured.

Attached is the graph.


So, my question was:
Deduce the volume of nitrogen dioxide formed.

I know the oxygen is in excess and thus 25cm3 of oxygen reacted with 50cm3 of nitrogen monoxide, to form 75cm3 of nitrogen dioxide. It adds up to me, I wrote 75cm3. However, the answer was 50cm3, they took the total volume formed - 25cm3 of oxygen, I don't understand why. Dont they react with each other, 50cm3 of NO and 25cm3 of O2?

Please help,
thank you so much!

What does the Gay-Lussac law state?
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Ter

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Re: Gas
« Reply #2 on: December 18, 2012, 04:40:37 AM »

Is it the same as Avogardo's law, that different gases with equal volumes and temperature and pressure will have equal no of particles? But how does this help..?

Btw, I'd like to confirm, different gases with equal volumes and temperature and pressure need not refer to only 1atm, 298K and 1atm, 273K onl right? Let's say the gases exist at the pressure 0.5 atm and temperature 300K, no of particles in the gases will still be the same wont it?

Thank you so much!
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DrCMS

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Re: Gas
« Reply #3 on: December 18, 2012, 05:17:51 AM »

I know the oxygen is in excess

When is the oxygen in excess?

25cm3 of oxygen reacted with 50cm3 of nitrogen monoxide, to form 75cm3 of nitrogen dioxide. It adds up to me, I wrote 75cm3.

Well you added it up wrong and did not consider the un-reacted oxygen or the molar volume of gases

If 25 moles of oxygen reacts with 50 moles of nitrogen monoxide how many moles of nitrogen dioxide are formed? 

What is the volume of the product compared with total of the two starting materials?

When 25cm3 (of the 50cm3) oxygen has reacted with 50cm3 of nitrogen monoxide how much oxygen is left and how much nitrogen dioxide has been formed.
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