# Question #51b13

##### 1 Answer

#### Explanation:

First of all, always use SI units to get the answer out in SI units. In this case, we want work and ∆E in joules, so use volume in m^3 and pressure in Pa.

You need the volume that the N2 gas occupies:

Note that the Ideal Gas Law will give you the same volume.

As the initial volume is zero:

Now substitute the external pressure (convert 1 atm to Pa) and the change in volume into the expression for work done:

By using SI units, the answer has come out neatly in J, as

The heat released is the enthalpy change:

Rearranging the formula for enthalpy allows us to solve for the internal energy change:

From the system's point of view, this means that during the reaction 2340 J was transferred as heat to the surroundings and a further 126.5 J was expended as expansion work, giving a total internal energy change/loss (∆E) of 2466.5 J.