Electrochemistry. Urgent. Please Help. (1 Viewer)

[Michaelmoo]

Which of the following displacement reactions can occur spontaneously?

Ag(I) with Cu(II)

Sn with pb(II)

Fe(II) with Mg

Al(III) with Ni

I understand that a positive EMF will result in the reaction occuring spntaneously. But I can;t seem to get it here. Any suggestions?

Thanks in Advance.

 

[kwabon]

Which of the following displacement reactions can occur spontaneously?

Ag(I) with Cu(II)

Sn with pb(II)

Fe(II) with Mg

Al(III) with Ni

I understand that a positive EMF will result in the reaction occuring spontaneously. But I can;t seem to get it here. Any suggestions?

Thanks in Advance.

kk first u need o know the reactivity series
K, Na, Li, Ba, Ca, Mg, Al, Zn, Fe, Sn, Pb, Cu, Ag, Pt, Au
since u noe this now, we can state that of two metals the more reactive metal is the one which willl displace the other metal from a solution of its ions.
for the first one: Ag(I) with Cu(II)
obviously Cu is gonna be oxidized, since it is more reactive.
refering to the standard potentials we can see Cu has .52V and Ag has .80Vso u flip Cu and make it a reduction half equation and in the process u flip the sign as well
so it basically becomes .8-.52 = which will give a positive number and thus the reaction is spontaneous.

for the second one: Sn with pb(II)
follow the steps and u will get that Sn is more reactive than Pb and thus Sn is getting oxidised and therefore u flip the half euation at the standard potentials for Sn and thus
.14-.13 = which gives a positive number and thus is spontanoeus

third one: Fe(II) with Mg
same procedure Mg is more reactive than Fe, flip Mg's half equation and thus
2.36-.44 = positive number and thus is spontanoeus

fourth one: Al(III) with Ni
again same procedure, Al is more reactive than Ni, flip Al's half equation
1.68 - .44 = gives a positive number and thus is spontanoeus


hopefully i am right and good luck

 

[Michaelmoo]

Ok But the wird thing is, is that they;ve actually written out the equations as follows:

Silver atoms react with copper ions

Lead Atoms react with Sn ions

Iron Atoms react with Magnesium ions

Nickel Atoms react with aluminium ions

 

[kwabon]

yeh, i am still pretty sure that its still gonna be the same thing. just ask ur teacher tomorrow or something, he/she will prolly explain it better. and who knows i may be wrong. so yeh just stick with wat u think is right. it always works for me

 

[Michaelmoo]

Aahhhh Ok. Yer cos the thing is its a multiple choice question. And I got an exam 2moz.. loll....

Dw Ill ask b4 skool or suming. Thanks anyway.

 

[kwabon]

damn quite stupid, i finally understand how to do it....u prolly noe it as well ... but for the sake of this thread i would like to correct myself.

ag (I) and Cu (II)
these cannot occur spontaneously since those two are ions and hence none of them can be reduced or oxidized
NON SPONTANEOUS

Sn and Pb (II)
okay so Sn is getting oxidized since only metal there and the ion is gettin reduced
therefore use the standard potentials and u will find out that they add up to .01 which is very close to 0 and will prolly not occur spontaneously
NON SPONTANEOUS

Fe (II) and Mg
righty so iron is the ion so its getting reduced and the magnesium is getting oxidised since it is the solid
use half equations and get the EMF as 1.92
SPONTANEOUS

Al (III) with Ni
same concept as the one above.....use half equations and then get the EMF as -1.44
NON SPONTANEOUS

i noe little too late, sorry bout that i couldnt help ya before but finally figured it out