Question

#1: What kind of reaction occurs when the entropy change of an endothermic reaction is negative?

A. spontaneous

B. reversible

C. nonspontaneous at equilibrium

D. irreversible

***my answer; C

is that right? @jim_thompson5910 :)

Answer 1

#2: What is the sign of ∆H in an exothermic process?

A. negative

B. positive

C. ∆H has no sign

***my answer: A. negative

(cuz endothermic is positive right? while exothermic is the negative one?)

is that right? :D

Answer 2

#3: An ice sculpture melts into a puddle of water. What is true of this reaction?

A. It is spontaneous.

B. Energy had to be added to the system for the reaction to occur.

C. The reaction happens faster if the ice sculpture is large.

D. No work is done in this reaction.

***Not too sure on this one.. I'm leaning towards A or B... what do you think of this one? :)

Answer 3

#4: Which of the following reactions is spontaneous?

A. lumps of sugar dissolving in water

B. sodium chloride forming sodium metal and chlorine gas

C. water freezing on a hot summer day

D. a mixture being separated

***My answer: A

i'm not 100% sure though.. what do you think? Does that look right to you? :)

Answer 4

#5: Consider the following equation:
NH4Cl --> NH3 + HCl, ∆H = +176 kJ/mol and ∆G = +98 kJ/mol
What kind of reaction is this at 300 K?

A. spontaneous

B. at equilibrium

C. nonspontaneous

***My answer: C

what do you think? does that look right to you? :D

Answer 5

1C looks good at least according to this page

http://answers.yahoo.com/question/index?qid=20110505110950AAWlfHw

Answer 6

ohh okay awesome! :P haha thanks :P

and lol that person wrote "My lonesome and very quarrelsome gray cells..." haha sooo funny lol :P

Answer 7

2A looks good as well

http://en.wikipedia.org/wiki/Exothermic_reaction

Answer 8

"by definition the enthalpy change has a negative value:

ΔH < 0

in an exothermic reaction"

Answer 9

ooh! yay :) so is that right though? exothermic = negative and endothermic=positive?

Answer 10

and equal doesn't exist i'm guessing? :/

Answer 11

i think so, that sounds familiar

Answer 12

okay yay :)

what about 3,4 and 5? :D

Answer 13

hmm one sec, i'm reading melting ice is an endothermic process

but some sources are saying it's a spontaneous process....hmm

Answer 14

okay :) yeah i got a bit confused on this one :/

Answer 15

idk what do you think? :)

Answer 16

i know that C and D are false, so they're out

Answer 17

okay :P yeah i narrowed it down to A and B too, but ehhh i got stuck lol :(

Answer 18

i feel like they are both correct to a certain extent... what do u think? :/

Answer 19

they both can't be correct, the very def of A is contrary to B

Answer 20

ohh okay.. so which do you think is more accurate? I'm lost :(

Answer 21

A looks like the better choice, but B looks good as well

if I were doing it, I would go with A i guess

Answer 22

okay sounds good :) i'll have to ask my teacher about this one lol :P tricky tricky :/ hahaa

Answer 23

gee i hope i don't get a problem like this on my final.. haha that would suck :(

Answer 24

haha what do you think of the other ones? :D

Answer 25

definitely, it would

Answer 26

haha well i guess on the final i'm just gonna have to make an educated (but kinda wild at the same time) guess lol :P and then cross my fingers, keep going on my final and pray i do well :P hehe

Answer 27

4A looks good

Answer 28

yayy :D

Answer 29

and i'm stuck on #5, hmm still thinking though

Answer 30

kk :)

Answer 31

kk :)