Copy of Change of Internal Energy - Prac 2 (5/28/2026)

Last updated about 3 hours ago

11 questions

Copy of Change of Internal Energy - Prac 2 (5/28/2026)

Last updated about 3 hours ago

11 questions

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? _______ How much work was done? _______ 

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 = _______ 