AAMC 5 #14...helpppp

[MrNeuro]

According to Equation 1, the concentration of the polymer with respect to [HPO42–] is:
A) n[HPO42–].
B) n2[HPO42–].
C) (1/n)[HPO42–].
D) (1/n2)[HPO42–].

Answer: C

nCDP => CPn + n HPO4

the part thats tripping me up is with respect to HPO42-

this is how i see it

1 CPn = n HPO4 (isnt this w/ respect to HPO4??????)

and

1/n CPn = HPO4
why isn't that the concentration of the polymer with respect to HPO4 because

what am i doing wrong

---

Members don't see this ad.

 

[EnginrTheFuture]

According to Equation 1, the concentration of the polymer with respect to [HPO42–] is:
A) n[HPO42–].
B) n2[HPO42–].
C) (1/n)[HPO42–].
D) (1/n2)[HPO42–].

Answer: C

nCDP => CPn + n HPO4

the part thats tripping me up is with respect to HPO42-

this is how i see it

1 CPn = n HPO4 (isnt this w/ respect to HPO4??????)

and

1/n CPn = HPO4
why isn't that the concentration of the polymer with respect to HPO4 because

what am i doing wrong

Let's analyze these two statements :

I) nCDP => CPn + n HPO4

II) 1 CPn = n HPO4 (isnt this w/ respect to HPO4??????)


what 1 is saying is that for every CDP used, the molecule of CPn is added to. It is still ONE CP molecule, but a little longer. With that said, for every CDP used (and elongation of the CPn molecule), there is one HPO4 created. So the number of CPn molecules we have in solution is always one, but the number of HPO4 grows n times. So you can re-phrase this to be the number of CPn molecules is the number of HPO4 molecules/n reactions taken place.

You can also think of this in terms of statement 2.It says that for every CPn molecule you have, n HPO4 were created. What you manipulated that equation to say is that for every HPO4 molecule you have, there's 1/n CPn molecules. This is because the number of reactions only increases the number of HPO4 molecules, not CPn. It ELONGATES the one molecule of CPn. This the number of molecules of CPn = (1/n)HPO4. # of molecules is analogous to concentration since they are in the same solution.


Hope that helps

Enginr

 

[typicalindian]

when I did this my ***** logic kicked in. I just said "each time you get 1 mole of CPn you get n moles of HPO4, so I reasoned it like this: if you get 5 moles of CPn, you're gonna have 5n moles of HPO4, which means [HPO4] = n*[CPn] therefore, [CPn]=1/n*[HPO4]. Does that make sense at all? It makes sense in my brain

 

[folktale]

"the concentration of the polymer with respect to [HPO42–]"

"with respect to" is the keyword. It's just saying what's the concentration of the polymer RELATIVE to that of HPO42-, not the actual concentration of HPO42- with respect to the polymer.

 

[folktale]

when I did this my ***** logic kicked in. I just said "each time you get 1 mole of CPn you get n moles of HPO4, so I reasoned it like this: if you get 5 moles of CPn, you're gonna have 5n moles of HPO4, which means [HPO4] = n*[CPn] therefore, [CPn]=1/n*[HPO4]. Does that make sense at all? It makes sense in my brain

I don't see the logic here. sorry. xP

 

[MrNeuro]

"the concentration of the polymer with respect to [HPO42–]"

"with respect to" is the keyword. It's just saying what's the concentration of the polymer RELATIVE to that of HPO42-, not the actual concentration of HPO42- with respect to the polymer.

can u write that out in math terms??

i get the fact that respect to here means that HPO4 is changing but when i try and write it out in equations it doesn't work

 

[folktale]

HPO42- increases with n, while the polymer is always one molecule with growing chain. As n increases, polymer stays one molecule, while HPO42- increases each time.

let's say n=1
1 HPO42- = CP

n=2
2 HPO42- = CP2

n=3
3 HPO42- = CP3 (Chris Paul represent lol)

So, back to the question, what's "the concentration of the polymer with respect to [HPO42–]":

this means that you're looking for the concentration of the polymer WITH RESPECT to HPO42-, which is the molecule in question here.

On this case, just carry over the coefficient on HPO42- to the polymer side, and you get 1/n(CPn), but since it's with respect to [HPO42-], you could just substitute CPn with HPO42- since we're comparing the concentration of the two with regards to HPO42-.

 

[typicalindian]

HPO42- increases with n, while the polymer is always one molecule with growing chain. As n increases, polymer stays one molecule, while HPO42- increases each time.

let's say n=1
1 HPO42- = CP

n=2
2 HPO42- = CP2

n=3
3 HPO42- = CP3 (Chris Paul represent lol)

So, back to the question, what's "the concentration of the polymer with respect to [HPO42–]":

this means that you're looking for the concentration of the polymer WITH RESPECT to HPO42-, which is the molecule in question here.

On this case, just carry over the coefficient on HPO42- to the polymer side, and you get 1/n(CPn), but since it's with respect to [HPO42-], you could just substitute CPn with HPO42- since we're comparing the concentration of the two with regards to HPO42-.

Isn't that the same thing I wrote?

 

[folktale]

Isn't that the same thing I wrote?

Haha, well that's how I see it. Maybe I thought yours was different b/c you didn't really elaborate on it.

 

[typicalindian]

Haha, well that's how I see it. Maybe I thought yours was different b/c you didn't really elaborate on it.

yeah I was too lazy to write out what happens between going from n to 5n in my example lol I just figured he'd see what I did.

 

[MrNeuro]

i over complicated this question smhh

Thanks guys

 

[HawaiiMedMan]

This thread just saved my sanity. Many thanks. Plus one more.

 

[CKinMN]

High fives all around. It just wasn't clicking.

 

[abottabeadr]

Sorry, not sure why the explanations above didn't make it click for me. But it did help my brain think about it as such:

Hopefully this helps someone.

I realize it's been roughly a decade since the initial post, but this is still the only worthwhile result when looking up the question.

 

[dyanir1284]

Sorry, not sure why the explanations above didn't make it click for me. But it did help my brain think about it as such:
View attachment 331591

Hopefully this helps someone.

I realize it's been roughly a decade since the initial post, but this is still the only worthwhile result when looking up the question.

This definitely helped!