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Ch.6 - Thermochemistry
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All textbooksTro 4th EditionCh.6 - ThermochemistryProblem 42

Chapter 6, Problem 42

A system absorbs 196 kJ of heat and the surroundings do 117 kJ of work on the system. What is the change in internal energy of the system?

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hey everyone in this example we need to calculate the change in internal energy for our system. If it's releasing 268 kg joules of heat and has 94 kg joules of work done on it. So we should recall our formula that our change in internal energy delta U. Is going to be equal to our value for heat which is represented by Q. Added to our value for work represented by W. So what we would say is that our change in internal energy is equal to our value for heat. Which in the problem is given as a release of kg joules. So that would be therefore negative to 68 kg joules so we can plug that in And this is going to be added to our value for work. So work is going to be done on the system. So we add positive 94 kg jewels. And this quantity is going to give us a value of -174. Kill it jules as our change in internal energy of our system. So this is our final answer. To complete this example. If you have any questions, please leave them down below and I will see everyone in the next practice video
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Identify each energy exchange as primarily heat or work and determine whether the sign of ΔE is positive or negative for the system. a. Sweat evaporates from skin, cooling the skin. (The evaporating sweat is the system.) b. A balloon expands against an external pressure. (The contents of the balloon is the system.) c. An aqueous chemical reaction mixture is warmed with an external flame. (The reaction mixture is the system.) Identify energy exchanges as primarily heat or work. Determine whether the sign of E is positive or negative for the system.

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Identify each energy exchange as primarily heat or work and determine whether the sign of ΔE is positive or negative for the system. Identify each energy exchange as primarily heat or work. a. A rolling billiard ball collides with another billiard ball. The first billiard ball (defined as the system) stops rolling after the collision. b. A book falls to the floor. (The book is the system). c. A father pushes his daughter on a swing. (The daughter and the swing are the system). Identify each energy exchange as primarily heat or work.

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A system releases 622 kJ of heat and does 105 kJ of work on the surroundings. What is the change in internal energy of the system?

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Textbook Question

We pack two identical coolers for a picnic, placing 24 12-ounce soft drinks and five pounds of ice in each. However, the drinks that we put into cooler A were refrigerated for several hours before they were packed in the cooler, while the drinks that we put into cooler B were at room temperature. When we open the two coolers three hours later, most of the ice in cooler A is still present, while nearly all of the ice in cooler B has melted. Explain this difference.

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