Destroyer #75 gchem

[yakuza]

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An unknown compound dissolves in water spontaneously. If the temperature of the water decreases, which is true?

the answer is delta G<0 , delta H>0 , delta S>0 (choice E)

I think I'm confused on the wording of the question. Let's say if the temperature decreases 0.0001 K, that doesn't necessarily mean delta H will be greater than zero. If temperature decreases by 100, I can understand why since you just look at it algebraically.

Also the basic law states G<0 , H<0 , S>0 = spontaneous (answer choice D)
If this is spontaneous at ALL temperatures, then how is it wrong?

 

[Thundercatz]

An unknown compound dissolves in water spontaneously. If the temperature of the water decreases, which is true?

the answer is delta G<0 , delta H>0 , delta S>0 (choice E)

I think I'm confused on the wording of the question. Let's say if the temperature decreases 0.0001 K, that doesn't necessarily mean delta H will be greater than zero. If temperature decreases by 100, I can understand why since you just look at it algebraically.

Also the basic law states G<0 , H<0 , S>0 = spontaneous (answer choice D)
If this is spontaneous at ALL temperatures, then how is it wrong?

Alex,

In this case, H is indeed positive because the temperature of the water decreased, meaning that heat/energy was absorbed from the surrounding into the system.

Choice D is true, but it doesnt fit the description.

 

[yakuza]

Thanks, I think I'm just over analyzing this problem.

Are you still taking your test tmrw?

 

[Thundercatz]

Thanks, I think I'm just over analyzing this problem.

Are you still taking your test tmrw?

No, I rescheduled it for the 30th. Gotta refresh the math. Dont want to give away free points hehe.

 

[yakuza]

lol I see. I think that's a smart idea. Have you been at UH everyday?

 

[Thundercatz]

lol I see. I think that's a smart idea. Have you been at UH everyday?

Yea, I been basically living there for the past 2 weeks. I hope I dont forget all the sciences actually. HAHA

 

[HoangDDS]

An unknown compound dissolves in water spontaneously. If the temperature of the water decreases, which is true?

the answer is delta G<0 , delta H>0 , delta S>0 (choice E)

I think I'm confused on the wording of the question. Let's say if the temperature decreases 0.0001 K, that doesn't necessarily mean delta H will be greater than zero. If temperature decreases by 100, I can understand why since you just look at it algebraically.

Also the basic law states G<0 , H<0 , S>0 = spontaneous (answer choice D)
If this is spontaneous at ALL temperatures, then how is it wrong?

The question said "spontaneously." C is the only choice that has deltaG<0. Therefore I would mark that already. But if you didn't catch that. It also said that the temperature of the water decrease, therefore it got colder, (Thudercatz said it ealier too), therefore delta H > 0 which is an endothermic reaction which absorbs heat from the surrounding which is why it is colder. Also question also said that you are DISSOLVING a cmpd in water--if you are dissolving anything in water you're creating disorder, which increases entropy, delta S >0 .

 

[HoangDDS]

lol, I took so long answering the question. I didn't know you already got it.

Good luck both of you.

 

[Thundercatz]

lol, I took so long answering the question. I didn't know you already got it.

Good luck both of you.

Hoang,

When you taking your test?

 

[HoangDDS]

Hoang,

When you taking your test?

Wassup Tuan, I'm taking it this Thrusday. 😱

 

[Thundercatz]

Wassup Tuan, I'm taking it this Thrusday. 😱

Good luck man! Im a week after you, and I am already feeling antsy!

 

[HoangDDS]

Good luck man! Im a week after you, and I am already feeling antsy!

haha, I'm trippin out. I feel like I still have a ton of stuff I need to solidfy before my test. And I feel like each day is ending faster and faster--and i dont even drink coffee!! 24hrs/day aint enough, I need 5 more!!

 

[yakuza]

lol, I took so long answering the question. I didn't know you already got it.

Good luck both of you.

lol well the more help the better. goodluck on the test