Chemistry Paper 4-theory- doubts =D

[Gémeaux]

Hey guys/gals, i just figured out that the cell potential of a viable reaction must be positive... did u know that? I didnt.. that's news to me

Sorry, could you elaborate that one?

 

[knowitall10]

Sorry, could you elaborate that one?

Umm.. i was just reading that chem guide site... it said that the cell potential of a viable reaction must be positive. you know how we calculate the overall cell potential when two half equations are given yeah? Yeah, that's basically supposed to be positive if we want to prove that the reaction does take place...if u dont get it, do u want me to post the link? It's an important point... u might wanna c it for yourself

 

[knowitall10]

http://www.chemguide.co.uk/CIE/section6/learningcdefgi.html#top
Voila!

 

[Gémeaux]

Umm.. i was just reading that chem guide site... it said that the cell potential of a viable reaction must be positive. you know how we calculate the overall cell potential when two half equations are given yeah? Yeah, that's basically supposed to be positive if we want to prove that the reaction does take place...if u dont get it, do u want me to post the link? It's an important point... u might wanna c it for yourself

http://www.chemguide.co.uk/CIE/section6/learningcdefgi.html#top
Voila!

Oh right, thankyou so much. I realize it now that all my answers were positive. But instead of using the expression E(right) - E(left) for cell potential, I always use E(reduced) - E(oxidized).

 

[knowitall10]

Oh right, thankyou so much. I realize it now that all my answers were positive. But instead of using the expression E(right) - E(left) for cell potential, I always use E(reduced) - E(oxidized).

Ahh.. u work the complicated way I use simple english

 

[PhyZac]

Oh right, thankyou so much. I realize it now that all my answers were positive. But instead of using the expression E(right) - E(left) for cell potential, I always use E(reduced) - E(oxidized).

First time to know that ! Jazaki Allah khairan!!

Now I wont forget In Sha Allah, both start with "R" right / reduced.

 

[knowitall10]

Oh so now everyone suddenly wakes up?


jk

 

[Ariel Robert]

Ahh.. u work the complicated way I use simple english

For a half equation the sign will only change when the equation changes the other way round... and hope you know that the salt bridge is KCl... In your diagram the equation for sulphur is S + 2e -> S^-2 so you must find the potential of this if in the data booklet is the other way round then you change the sign...

Also know that you can increase the voltage by increasing the potential difference between 2 elements you choose....

 

[knowitall10]

For a half equation the sign will only change when the equation changes the other way round... and hope you know that the salt bridge is KCl... In your diagram the equation for sulphur is S + 2e -> S^-2 so you must find the potential of this if in the data booklet is the other way round then you change the sign...

Also know that you can increase the voltage by increasing the potential difference between 2 elements you choose....

Hey, thanks brother... can u explain that last line again please?
And Gémeaux Ariel Robert here is saying the sign does change, u might wanna pay attention...

 

[knowitall10]

For a half equation the sign will only change when the equation changes the other way round... and hope you know that the salt bridge is KCl... In your diagram the equation for sulphur is S + 2e -> S^-2 so you must find the potential of this if in the data booklet is the other way round then you change the sign...

Also know that you can increase the voltage by increasing the potential difference between 2 elements you choose....

btw, my book says that the salt bridge is "can be made from a strip of filter paper soaked in a satursted solution of potassium nitrate".. but i'm going to beleive u cz i heard my teacher say something similar to ur statement (i think).
Jazak Allahu Khair anyway (I think ur Muslim No offense if u arent)

 

[knowitall10]

Did u guys go back to sleep again?







Jk.. sorry..

 

[knowitall10]

Hello? Brother Ariel Robert , now that u mentioned that last line, cn u please explain....

 

[Ariel Robert]

Hey, thanks brother... can u explain that last line again please?
And Gémeaux Ariel Robert here is saying the sign does change, u might wanna pay attention...

if you took an element with a potential of +0.52 and another one with -0.04, The voltage will be +0.52-(-0.04) = 0.56V
And if you take the +0.52 again but take another one which will give more voltage like -0.44, the voltage now will be higher = 0.96V, this way you can increase the voltage of a cell...

I said this because there are question asking "how will you increase the voltage of a cell?"...

 

[Gémeaux]

And Gémeaux, Ariel Robert here is saying the sign does change, u might wanna pay attention...

No no no. The sign does Not change! At least that is how I've been attempting my questions so far..

btw, my book says that the salt bridge is "can be made from a strip of filter paper soaked in a satursted solution of potassium nitrate"..

It can be either. Both KCl and KNO3 are correct.

 

[Ariel Robert]

btw, my book says that the salt bridge is "can be made from a strip of filter paper soaked in a satursted solution of potassium nitrate".. but i'm going to beleive u cz i heard my teacher say something similar to ur statement (i think).
Jazak Allahu Khair anyway (I think ur Muslim No offense if u arent)

Even the book is correct but i use KCl cuz its easy to understand...

 

[knowitall10]

if you took an element with a potential of +0.52 and another one with -0.04, The voltage will be +0.52-(-0.04) = 0.56V
And if you take the +0.52 again but take another one which will give more voltage like -0.44, the voltage now will be higher = 0.96V, this way you can increase the voltage of a cell...

I said this because there are question asking "how will you increase the voltage of a cell?"...

Ooooooooohhh... got it! Thanks a lot!!! and please excuse me for being so annoying- i am wake for 20 hrs straight :/ and i was "smart" to drink coffee an hour ago so... anyway..Jazak Allah!
But now who's word should i take? Does it change or does it not change?

 

[Ariel Robert]

No no no. The sign does Not change! At least that is how I've been attempting my questions so far..


It can be either. Both KCl and KNO3 are correct.

The sign does change, you check again...

 

[knowitall10]

The sign does change, you check again...

LOL! It's so cool to watch this
I'm sorry nope, not cool :/
The thing is, i wouldnt have been asking ths, but za broblem (Arab way of saying "the problem" ) is that my school teacher says that yep, it changes, but my tutor says, nope batai, it will never change... its not just amongst u... this confusion will still grow when every1 wakes up

 

[Ariel Robert]

ok i have question for you

the potential for Ag^+1 + 1e -> Ag is +0.80
what's the potential for Ag -> Ag^+1 + 1e ?

 

[knowitall10]

ok i have question for you

the potential for Ag^+1 + 1e -> Ag is +0.80
what's the potential for Ag -> Ag^+1 + 1e ?

Bro... why u challengin us? I BELIEVE YOU!!! Oh God.. never mind, it will......umm..change? yeah, it'll change: