Use your notes (Thermochemistry Part 1) and the examples provided to you in class to assist you with answering the following questions.
Formula needed:
ΔU = q + w
w = ΔU - q
q = ΔU - w
You must include the correct units in your answers.
The internal energy of a system increased by 982 J when it absorbed 492 J of heat. Was work done by or on the system?
If a cellphone does 200 kJ of work and released 100 kJ of heat, what is the change of internal energy for the device?
In the formula ΔU = q + w, work done by the system during expansion is , and heat by the system is positive.
A system gives off 455 kJ of heat and the surroundings does 127 kJ of work on the system. What is the internal energy of the system?
The internal energy of a system is currently at 275 kJ and the system is doing 125 kJ of work. What was the overall heat of the system?
A system is receiving 3.22 J of heat and the surroundings are having work done on them. The system does 2.54 J of work. What is the internal energy of the system?
When do we calculate the internal energy of the surroundings?
The surroundings gain 255 kJ of heat while they were doing 101 kJ of work on the system. What is the internal energy of the system?
If a system has 455 kJ of heat and its internal energy was 401 kJ, calculate the overall work done and determine if the system or the surroundings were doing the work.
w =
what did the work?
A system has 644 kJ of internal energy and is doing 855 kJ of work. Determine the heat. Identify if this is an endothermic or exothermic reaction and briefly explain why.
q =
reaction type
why?
a.) Calculate w for a system that absorbs 260 kJ of heat and for which ΔU = 157 kJ.
b.) Is the work done on or by the system?
c.) Does the system expand or contract (review the section of the notes on expansion and compression)?
a =
b =
c =