Gas Laws Question - Please Help

[jruiz3]

Consider the following chemical equation.

2NO2 ----> N2O4

If 18.7 mL of NO2 gas is completely converted to N2O4 gas under the same conditions, what volume will the N2O4 occupy?

? mL

[adrian]

at the same pressure and temperature, half, i.e. 18.7/2=9.35 mL.

[jruiz3]

adrian thank you so much. your a great help

[Paul Robbins]

Originally Posted by jruiz3

Consider the following chemical equation.

2NO2 ----> N2O4

If 18.7 mL of NO2 gas is completely converted to N2O4 gas under the same conditions, what volume will the N2O4 occupy?

? mL

I'm not a fan of this sort of question which says "under the same conditions". I think it's better to describe some actual conditions so that people think about the reality of the experiment.

When the number of moles of gas is halved, it's only possible to have "the same conditions" if the experiment is done in a flexible container, like a balloon. The volume will be halved in these circumstances.

BUT, if the reaction is carried out in a rigid container - most lab apparatus is rigid - the volume of the gas will stay the same. (A gas will always spread out to fully occupy a container.) Then, instead of the volume being halved, the pressure will be halved.

[KathChem82]

hi! this question actually puzzles me. the "the same conditions" of course mean the same temperature, same pressure, etc. So the only thing that changed here is the volume. Is the container rigid or elastic? Is it a solid cylinder or a balloon? Because these variables (volume, pressure, temperature) are inter-related. One variable influences the other. Say, if pressure is increased, volume decreases. Now, if the container where the conversion of NO2 to N2O4 occurs is something rigid and closed, would the volume not stay the same? The gases take the volumes of their containers right?

[NanoMachine]

I think Paul answered your questions before you asked them.

[KathChem82]

yes nano. but i just want to ask jruiz about it, maybe he can tell the specifics. just so that the answer to his questions can be backed up with proper calculations.