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ok that whole ice melting and forming of exothermic and endothermic just went out the window for me
in destroyer there are 4 questions that are making me go crazy someone please CLEARLY explain why they are different
41. H2Ol + H2Ol----> OHaq + H3O aq When the temperatur is decreased from 25C it is found that Kw has decreased. which of the following is true?
a. the rxn must be exothermic
b. the rxn must be endothermic
the solution says that since temp is decreausing it is exothermic but since Kw has decreased it has to be endothermic...what does Kw stand for again bc singce the reactants are liquid would they even count in Kw or am i thining of equilibrium constant.........that not the main problem here im paying attention to the fact in that the solution says decreasing temp will favor exothermic...and iftemp is eincreasing it will favor endothermic.
75.An unknown cmpd dissolves in H2O spontaneously. If the temp of the water decreases, which is true?
answer: delta G<0,DeltaH>0,deltaS>0
ok i understand the G and the S part.....but why is delta H positive...i know for rxn to be spontaneous it can be (-)deltaH, (+)deltaS....or it can be positive for both but at high temp....so since temp is decreasing wouldnt it be better to answer the safe route for a spontaneous rxn which is ALWAYS SPONTANEOUS can be (-)deltaH, (+)deltaS....and the other thing it says the temp of water is decreasing...Q41 says that this will favor exothermic rxn...so another reason why i think delta H should be<0
126. Ammonium nitrate will dissolve in water at 25C and a decrease in temp is noted...which of the following is true?
answer:C positive Delta H and positive Delta S...if some1 can explain Q75 pretty well im assuming it will be the same thing for this but maybe not.....newqays im gooing after again what Q41 said decreasing temp favvors exothermic rxn...but the solution for this says that since temp decreased the rxn is endothermic
133. Which staement is False?
a. if a rxn is exothermic, the system evolves hee to the surroundings
b. During an exothermic rxn, a chemical substance increases in potential energy
c. During an endo thermic rxn, the temp of the surroundings is lowered
d. b and c
e. a and b
answer is B
i know that B is falso so dont worry bout explaining that
and i also know A is true so dont worry bout that either
C i have a problem with.again according to Q41...decreasing temp favor exothermic rxn
originally i had it figure that when ice melts bonds are broken and heat is absorbed making an endothermic rxn. on the other hand, when ice is formed...bonds are formed....heat is released making it an exothermic rxn...but my thinking was wrong in the fact that i associated making ice with decreasing temp since it needs to get cold to form ice. this thinking is wrong for questions 75,126, and 133 but works for 41.
I know i put a lot of stuff up here but im sure there is an easy way to this im just not understanding why sometimes temp dec is exothermic and other times is endothermic....please give me insight in each example
in destroyer there are 4 questions that are making me go crazy someone please CLEARLY explain why they are different
41. H2Ol + H2Ol----> OHaq + H3O aq When the temperatur is decreased from 25C it is found that Kw has decreased. which of the following is true?
a. the rxn must be exothermic
b. the rxn must be endothermic
the solution says that since temp is decreausing it is exothermic but since Kw has decreased it has to be endothermic...what does Kw stand for again bc singce the reactants are liquid would they even count in Kw or am i thining of equilibrium constant.........that not the main problem here im paying attention to the fact in that the solution says decreasing temp will favor exothermic...and iftemp is eincreasing it will favor endothermic.
75.An unknown cmpd dissolves in H2O spontaneously. If the temp of the water decreases, which is true?
answer: delta G<0,DeltaH>0,deltaS>0
ok i understand the G and the S part.....but why is delta H positive...i know for rxn to be spontaneous it can be (-)deltaH, (+)deltaS....or it can be positive for both but at high temp....so since temp is decreasing wouldnt it be better to answer the safe route for a spontaneous rxn which is ALWAYS SPONTANEOUS can be (-)deltaH, (+)deltaS....and the other thing it says the temp of water is decreasing...Q41 says that this will favor exothermic rxn...so another reason why i think delta H should be<0
126. Ammonium nitrate will dissolve in water at 25C and a decrease in temp is noted...which of the following is true?
answer:C positive Delta H and positive Delta S...if some1 can explain Q75 pretty well im assuming it will be the same thing for this but maybe not.....newqays im gooing after again what Q41 said decreasing temp favvors exothermic rxn...but the solution for this says that since temp decreased the rxn is endothermic
133. Which staement is False?
a. if a rxn is exothermic, the system evolves hee to the surroundings
b. During an exothermic rxn, a chemical substance increases in potential energy
c. During an endo thermic rxn, the temp of the surroundings is lowered
d. b and c
e. a and b
answer is B
i know that B is falso so dont worry bout explaining that
and i also know A is true so dont worry bout that either
C i have a problem with.again according to Q41...decreasing temp favor exothermic rxn
originally i had it figure that when ice melts bonds are broken and heat is absorbed making an endothermic rxn. on the other hand, when ice is formed...bonds are formed....heat is released making it an exothermic rxn...but my thinking was wrong in the fact that i associated making ice with decreasing temp since it needs to get cold to form ice. this thinking is wrong for questions 75,126, and 133 but works for 41.
I know i put a lot of stuff up here but im sure there is an easy way to this im just not understanding why sometimes temp dec is exothermic and other times is endothermic....please give me insight in each example
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