Achieve Question 17

[Lidia_1I]

Can someone please explain how to do this problem.

A 0.877 mol sample of NO2(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 17.9 K. Calculate the amount of heat q required to bring about this temperature change, and find the corresponding total change in the internal energy ΔU of the gas.

Assume that the constant‑pressure molar specific heat for NO2(g), which consists of nonlinear molecules, is equal to 4R, where R=8.3145 J/(mol·K) is the ideal gas constant.

q=
ΔU=

[Shail Patel 3A]

This question can be broken down into two parts:

1) Finding q:

For this part, you should be able to just use q=nCdeltaT. Take the number of moles and multiply by 4R times 17.9K.


2) Finding deltaU

I found this step challenging, but I approached it by finding the work the system does and adding this value to q. the work the system does can be calculated by w = -pdeltaV. You will find delta V by using PV=nRT based on the given data and plugging in for initial values and final values. The result should be a negative value since the system is doing work of expansion. You may then add this to q to find a total change in internal energy.

Hopefully this help!

[yesmal1J]

To find Q, you would use the equation Q=(n)(C)(ΔT). With n being the number of moles, C being the molar specific heat (4R), and ΔT being temperature.

To find ΔU, the equation provided is Cv = Cp - R. The molar specific heat is then 3R (4R-R). You would then replace your original value for C when you were solving Q (Q=(n)(C)(ΔT)) as 3(8.3145) rather than 4(8.3145). That should give you your final answer!