# Can someone help me with this question please?

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Under certain conditions, the well-known fertilizer ammonium nitrate (NH4NO3) explodes according to the following balanced equation:

2NH4NO3(s) → 2N2(g) + 4H2O(g)+ O2(g)

Exactly 577 g of ammonium nitrate is placed in a 33.59 L constant-volume container containing dry air at 489.9 kPa and 29 ºC. The container is heated to 456 ºC and an explosive reaction occurs. It may be assumed that the reaction goes to completion. Luckily, the container remains intact after the explosion. Determine the mole fraction of nitrogen (N2) in the gas phase after the explosion.  Round your final answer to two significant figures.

Data: Assume that the composition of dry air is 79% N2 and 21% O2 by volume.

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Posted (edited)

From the given equation calculate the mole of all gases, water is steam. Second from the given volume of the Container minus the volume of the solid salt calculate also the mole of nitrogen and oxygen of the air. Summarize of all moles and build the quote of nitrogen to the summery.

Edited by chenbeier
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6 hours ago, Milani said:

Under certain conditions, the well-known fertilizer ammonium nitrate (NH4NO3) explodes according to the following balanced equation:

2NH4NO3(s) → 2N2(g) + 4H2O(g)+ O2(g)

Exactly 577 g of ammonium nitrate is placed in a 33.59 L constant-volume container containing dry air at 489.9 kPa and 29 ºC. The container is heated to 456 ºC and an explosive reaction occurs. It may be assumed that the reaction goes to completion. Luckily, the container remains intact after the explosion. Determine the mole fraction of nitrogen (N2) in the gas phase after the explosion.  Round your final answer to two significant figures.

Data: Assume that the composition of dry air is 79% N2 and 21% O2 by volume.

Where is this from ?

Surely it is a trick question, I have never seen so many distractors in a question before.

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It's a practice question for my chem class. Could you please help? I am not understanding what to do as my teacher doesn't teach properly.

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Posted (edited)

First convert the 577 g Ammonium nitrate into mol. You need molar mass for it. n = m/M

From the chemical equation you see that 2 mol ammoniumnitrate refers to 2 mol nitrogen, 4 mol water and 1 mol oxygen.

From the calculate mole above get them for the gases.

look up specific gravity of NH4NO3 calculate the volume.

From the given volume of the container subtract it.

This volume is air. With the given pressure, temperatur and calculated volume use ideal gas law before explosion and get mol of air. Separate this to 79% nitrogen and 21% oxygen. Add all moles

Mol fraction is

Mf = nN2/(nN2+nO2+nH2O)

Edited by chenbeier
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2 hours ago, Milani said:

It's a practice question for my chem class. Could you please help? I am not understanding what to do as my teacher doesn't teach properly.

So this is homework/classwork.

So it should be posted in homework help and you should tell us what you do know about the subject and at what point you came across something you don't understand.

That is what have you done so far ?

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9 hours ago, chenbeier said:

First convert the 577 g Ammonium nitrate into mol. You need molar mass for it. n = m/M

From the chemical equation you see that 2 mol ammoniumnitrate refers to 2 mol nitrogen, 4 mol water and 1 mol oxygen.

From the calculate mole above get them for the gases.

look up specific gravity of NH4NO3 calculate the volume.

From the given volume of the container subtract it.

This volume is air. With the given pressure, temperatur and calculated volume use ideal gas law before explosion and get mol of air. Separate this to 79% nitrogen and 21% oxygen. Add all moles

Mol fraction is

Mf = nN2/(nN2+nO2+nH2O)

Hi, Thanks for your response.

I tried your method but am still having some trouble. Do we calculate the mole of all the gases?

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Yes from the mole of the ammoniumnitrate you have to calculate according the chemical reaction of all gases.

Additionall you have to add the air.

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On 10/7/2021 at 8:37 AM, chenbeier said:

First convert the 577 g Ammonium nitrate into mol. You need molar mass for it. n = m/M

From the chemical equation you see that 2 mol ammoniumnitrate refers to 2 mol nitrogen, 4 mol water and 1 mol oxygen.

From the calculate mole above get them for the gases.

look up specific gravity of NH4NO3 calculate the volume.

From the given volume of the container subtract it.

This volume is air. With the given pressure, temperatur and calculated volume use ideal gas law before explosion and get mol of air. Separate this to 79% nitrogen and 21% oxygen. Add all moles

Mol fraction is

Mf = nN2/(nN2+nO2+nH2O)

which temperature would you use to calculate the volume, the initial volume before being heating or after?

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Neither nor, the volume is given of the container and is constant. The volume of the salt calculate before explosion.

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