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Quiz 1a _solution_

# Quiz 1a _solution_ - Since we know the brick starts out at...

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P7A Quiz 1a DL Sec ___ Name ( last ) _______________________ ( first ) ____________________ |__|__|__| Student ID _________________________ first 3 letters last name I certify by my signature that I will abide by the code of academic conduct of the University of California. Signature ________________________________________ NOTE: As always, you will be graded on the quality of your response. Rubric Codes: 1. A single ice cube (m=0.25kg) at 0 C⁰ is dropped into a large insolated container of alcohol at room temperature (23 C⁰). Draw a complete Energy System Diagram for the process of these two substances reaching thermal equilibrium. You should assume the ice cube completely melts in this process. 2. Below is the heat curve for a brick of an unknown metal. Considering that the metal is currently solid and at 150 K , how much heat will be needed to melt exactly ½ of the initial amount?
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Unformatted text preview: Since we know the brick starts out at 150 K ⁰ , we know where on the heat curve we begin (green arrow). To melt half of our brick, we need to travel half the way to completely melted, which will be to the red arrow. The question asks us to find the energy needed to go from the green arrow to the red arrow. This is 4250kJ-750kJ= 3500kJ . Water Alcohol Energy System Diagram Checklist: Values of all known indicators Algebraic statement of energy conservation Labeled different substances Indicated if system is open or closed. 50 100 150 200 250 300 350 400 450 500 550 600 650 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 Temperature (K⁰) Energy Added (kJ) E b m(l) i =0kg m(l) f =0.25kg E th T i = 23 C⁰ T f =? (<23 C⁰ ) ∆ E th + ∆ E b =0, closed system...
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