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Need help calculating Internal energy

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Wienerbroed:
I need help solving a question about finding the change in internal energy.
The question is:

When it explodes, nitroglycerin splits into nitrogen gas, carbon dioxide, oxygen and water vapor. The enthalpy of formation is -365,0 kJ/mol for nitroglycerin, -393,5 kJ/mol for carbon dioxide and -241,8 kJ/mol for water vapor.
Calculate the enthalpy of reaction (ΔH) as well as the change in internal energy (ΔU) when nitroglycerin completely decomposes with a constant pressure of one bar. Assume an ideal gas is formed, that performs volume change work.

I've been able to calculate the ΔH, but I do not know how to calculate the ΔU. I know that I'm supposed to use
ΔU = q + w and PV = nRT, but I don't know how.

Borek:
Reaction equation would probably help.

Orcio_87:
@Wienerbroed

Did you read about enthalpy definition ?

ΔH = ΔU + pΔV

Here pressure is constant so the second term (pΔV) relies only on the gaseous products (water is also included as a gas).

Wienerbroed:
@Orcio_Dojek

Yes, I am aware of that, however I do not know how to get a measurement for the change in volume.

Borek:

--- Quote from: Wienerbroed on June 26, 2021, 05:05:39 PM ---Yes, I am aware of that, however I do not know how to get a measurement for the change in volume.

--- End quote ---

And that's where the reaction equation comes to the rescue.

How many moles of gas before? After? Can you use this information to calculate ΔV?

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