CEM 142 First Exam Latest Update Already Passed

CEM 142 First Exam Latest Update Already Passed Define and give examples of open, closed and isolated systems Open system-both matter and energy can enter or leave (beaker without a lid, pour your hot drink into a mug) Closed system- the amount of matter is constant and only energy can enter or leave (cup of coffee with a lid on it) Isolated systems- neither energy nor matter would move between the system and the surroundings (Styrofoam coffee cup with a lid on) Explain the difference between state and path functions and give examples. state- heat change at a constant pressure, enthalpy. DOES NOT depend on the path taken. (height of mt. everest) path- functions that depend on the path (distance traveled, amount you deposit) endothermic and exothermic Exothermic-bonds being made, give out energy, heat out, temp up gas-- liquid -- solid Endothermic-bonds being broken, take energy in from surroundings, get colder, heat in solid--liquid--gas Identify the direction of the thermal energy change and the sign of q or ΔH for a phase change. Explain the role of probability in entropy changes. more molecules will be randomly distributed and will move towards a random distribution from an orderly distribution Predict the sign of the entropy change for simple systems. gases have more entropy than solids, if delta s is positive then disorder increases Explain the second law of thermodynamics in terms of the system and surroundings. tells us that we cannot even get back the energy that we use to bring about a change in a system Explain why we usually use ΔG instead of the total entropy change to predict whether a process is thermodynamically favorable. because you can't measure the entropy of the universe very well. delta g focuses on system and easy to measure that. more accurate Chapter 5 BIG IDEAS The temperature at which a phase change occurs depends upon the molecular structure of the compound. As a molecular substance changes phase, intermolecular