A gaseous reaction occurs at a constant pressure of 45.0 atm and releases 62.5 Kj of heat. Before the reaction, the volume of the system was 8.60 L . After the reaction, the volume of the system was

3.00 L.
Calculate the total internal energy change in kilojoules.

To calculate the total internal energy change, you can use the equation:

ΔU = q + w

where ΔU is the change in internal energy, q is the heat transferred to or from the system, and w is the work done on or by the system.

In this case, the given information is that q = -62.5 kJ (since heat is released) and the pressure is constant, so there is no work done (w = 0).

Therefore, the total internal energy change (ΔU) is:

ΔU = q + w
ΔU = -62.5 kJ + 0
ΔU = -62.5 kJ

So, the total internal energy change is -62.5 kJ.

To calculate the total internal energy change, we will use the equation:

ΔU = q + w

where ΔU is the change in internal energy, q is the heat transferred, and w is the work done.

In this case, we are given the heat released, q = -62.5 kJ (note the negative sign since heat is released).

To find the work done, we need to determine the change in volume of the system, ΔV.

ΔV = Vf - Vi
= 3.00 L - 8.60 L
= -5.60 L (again, note the negative sign indicating a decrease in volume)

Now we'll use the equation for the work done in a gas expansion or compression:

w = -PΔV

where P is the pressure and ΔV is the change in volume.

In this case, the pressure is constant at 45.0 atm and the change in volume is -5.60 L.

w = -45.0 atm * (-5.60 L)
= 252.0 L·atm

Since the unit of work in the equation is L·atm, we need to convert it to joules (J) to match the unit of heat (kJ).

1 L·atm = 101.325 J

So, w = 252.0 L·atm * 101.325 J/L·atm
= 25,522.2 J

Finally, we can calculate the total internal energy change:

ΔU = q + w
= -62.5 kJ + 25,522.2 J (converting kJ to J)
= -62,500 J + 25,522.2 J
= -36,977.8 J

Since the question asks for the answer in kilojoules (kJ), we divide by 1000:

ΔU = -36,977.8 J / 1000
= -36.98 kJ (rounded to two decimal places)

Therefore, the total internal energy change is approximately -36.98 kJ.