Summary

This document is a lecture presentation on thermodynamics, covering topics like the first law of thermodynamics, enthalpy, exothermic and endothermic reactions and their real-life applications. Includes examples, diagrams, and a summary.

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THERMODYNAMICS Rellian S. Colita COMPETENCIES explain the first law of thermodynamics explain enthalpy of a reaction THERMODYNAMICS a branch of science which deals with the study of heat and temperature and their relation to other forms of energy Heat and Work Work can be used to creat...

THERMODYNAMICS Rellian S. Colita COMPETENCIES explain the first law of thermodynamics explain enthalpy of a reaction THERMODYNAMICS a branch of science which deals with the study of heat and temperature and their relation to other forms of energy Heat and Work Work can be used to create heat. Heat and Work The opposite is also true: heat can be used to create work. as the heat boils the water, it will do work on the balloon, making it expand Internal Energy= U Two Types of Reaction Two Types of Reaction EXOTHERMIC REACTIONS ENDOTHERMIC REACTIONS Differences between Endothermic and Exothermic reactions First Law of Thermodynamics The change in the internal energy of a system is equal to the amount of heat supplied to the system minus the amount of work done on its surroundings. ΔU=change in internal energy Q =heat added W=work done by the system The Sign Conventions Q is positive if the heat added to the system W is positive if work is done by the system Q is negative if heat leaves the system W is negative if work is done on the system Isovolumetric – volume doesn’t change → no work done (W = 0) Isothermal – temperature doesn’t change → no change in internal energy (∆U = 0) Adiabatic – thermally insulated → no energy transferred as heat (Q = 0) Isolated System → no energy transferred as heat, no work done by system, no change in internal energy (W = ∆U = Q = 0) EXAMPLE #1 3000 J of heat is added to a system and 2500 J of work is done by the system. What is the change in internal energy of the system? Given: Solution: Heat (Q) = +3000 Joule ΔU = Q-W Work (W) = +2500 Joule ΔU = 3000-2500 ΔU = 500 Joule EXAMPLE #2 2000 J of heat is added to a system and 2500 J of work is done on the system. What is the change in internal energy of the system? Solution: Given: ΔU = Q-W Heat (Q) = +2000 Joule ΔU = 2000-(-2500) Work (W) = -2500 Joule ΔU = 2000+2500 ΔU = 4500 Joule Drill 1 Suppose 40.00 J of energy is transferred by heat to a system, while the system does 10.00 J of work. What is the net change in the system’s internal energy? ΔU= Q − W =40.00 J − 10.00 J =30.00 J. Drill 2 Heat transfers 25.00 J out of the system, while 4.00 J is done by work on the system. What is the net change in the system’s internal energy? ΔU= Q −W = −25.00 J − (−4.00 J) = −21.00 J Drill 3 A gas has constant pressure in a system. There is a loss of 45 J of heat in the surroundings around the system. 450 J of work is done onto the system. Find the system’s internal energy? ΔU = Q-W ΔU = 45J - (- 450J) ΔU = 495J Real Life Applications SUMMARY if heat is added to the system, then the internal energy of the system increases if heat leaves the system, then the internal energy of the system decreases if the work is done by the system, then the internal energy of the system decreases if the work is done on the system, then the internal energy of the system increases Refere nce Bayquen, A. & Peña, G., (2022). Exploring Life Through Science Series - General Chemistry 2 (SHS). Quezon City, Philippines. Phoenix Publishing House, Inc. Assessment: Written Quiz w/ LQ #1 Please study the topics under 3rd quarter week 1 to week 5. The assessment will be posted on Friday at 4:45 PM. It will be closed on Sunday at 11:59 PM. Do well, kids! :) and clarifications, Google Chat: Rellian Colita Email: [email protected] Consultation CREDITS: This presentation time: template was created by Slidesgo, THU, 1:10 including P.M.and- 1210 icons by Flaticon, infographics & images by Freepik P.M. Please keep this slide for attribution

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