What is the change in internal energy (in J) of a system that absorbs 0.246 kJ of heat from its surroundings and has 0.771 kcal of work done on it?
Is this correct?
0.246, kJ x (1000 J/1 kJ) = 246 J
0.771 kcal x (4184 J/1 kcal) =3225.86 j
246 J + 3225.86 J = 3471.86 J
or 3.47186 x 10^3
is this correct?
Thank you.
absorbs heat = + (system loses heat = -)
work done on system = + (work done by system = -)
correct? yes and no. I don't see anything wrong with the calculation but you aren't allowed that many significant figures.
absorbs heat so q is +
work done on it is +
To determine the change in internal energy of the system, you need to consider the heat absorbed and the work done on the system. The change in internal energy (ΔU) is equal to the sum of the heat absorbed (Q) and the work done on the system (W).
First, let's convert the given values to joules for consistency:
0.246 kJ x (1000 J/1 kJ) = 246 J
0.771 kcal x (4184 J/1 kcal) = 3225.864 J or approximately 3226 J
Now, you can sum up the heat absorbed and the work done to find the change in internal energy:
246 J + 3226 J = 3472 J
So, the change in internal energy is 3472 joules (J).
Note: Your calculations are correct, and your final answer of 3.47186 x 10^3 J can also be written as 3471.86 J or simply 3472 J.