ronaldo23
02-03-2008, 09:32 PM
got it thanks
|
View Full Version : quick MCAT problem...can't figure answer ronaldo23 02-03-2008, 09:32 PM got it thanks adamber 02-03-2008, 09:35 PM C? Waterlilies 02-03-2008, 09:39 PM c :) ronaldo23 02-03-2008, 09:41 PM why? adamber 02-03-2008, 09:44 PM A cannot be correct, because the second law of thermo is never violated. D is incorrect, because deltaG= deltaH- TdeltaS, and delta S is decreasing, so overall it will be positive deltaG, which is non-spontaneous. B is backwards, because if the entropy of the system is decreasing, then the entropy of the surrounding must be increasing, since that maintains the second law of thermo. biggiesmallsiz 02-03-2008, 09:44 PM why? evaporation = lots of gas molecules = lots of entropy adding to the universe SketchLazy 02-03-2008, 09:47 PM When dissolved sugar is recrystallized by evaporating the water, its entropy decreases. A crystal is more ordered than particles in solution. In terms of thermodynamics, this must mean that A the second law of thermodynamics is broken. B the entropy of some other part of the system is increased. C the entropy of the universe is increased. D evaporation will occur spontaneously. I think it's B. The water that is dissolving the sugar is also part of the system. When it evaporates, its entropy increases because it is becoming a gas. biggiesmallsiz 02-03-2008, 09:54 PM I think it's B. The water that is dissolving the sugar is also part of the system. When it evaporates, its entropy increases because it is becoming a gas. its def C jesus christ. do you have the answer? adamber 02-03-2008, 09:57 PM I think it's B. The water that is dissolving the sugar is also part of the system. When it evaporates, its entropy increases because it is becoming a gas. The water is part of the system originally, but when it evaporates, the gas molecules contribute to the entropy of the surroundings by spreading out further. Revilla 02-03-2008, 10:31 PM Another vote for C here. |