Email
Chat with tutor
logo

Ask Questions, Get Answers

X
 
Answer
Comment
Share
Q)

By how much is oxidizing power of $MnO_4^-/Mn^{+2}$ couple decreases if the $H^+$ concentration is decreased from 1M to $10^{-4}$M at $25^{\large\circ}C$ .Assume other species have no change in concentration.

$\begin{array}{1 1}(a)\;0.37V\\(b)\;0.35V\\(c)\;0.4V\\(d)\;0.28V\end{array}$

1 Answer

Comment
A)
In acidic medium $MnO_4^-$ acts as oxidizing agent as per the reaction.
$MnO_4^-+8H^++5e^-\rightarrow Mn^{+2}+4H_2O$
$E_1=E^0_{MnO_4^-/Mn^{+2}}-\large\frac{0.059}{5}$$\log \large\frac{[Mn^{+2}]}{[MnO_4^-][H^+]^8}$
$\Rightarrow E^0_{MnO_4^-/Mn^{+2}}-\large\frac{0.059}{5}$$\log \large\frac{[Mn^{+2}]}{[MnO_4^-][1]^8}$
$E_2=E^0_{MnO_4^-/Mn^{+2}}-\large\frac{0.059}{5}$$\log \large\frac{[Mn^{+2}]}{[MnO_4^-][10^{-4}]^8}$
$\therefore (E_1-E_2)=\large\frac{0.059}{5}$$[\log \large\frac{[MnO_4^-]}{[Mn^{+2}]}\large\frac{[Mn^{+2}]}{[MnO_4^-][10^{-4}]^8}]$
$\Rightarrow 0.377V$
Thus oxidising power of $MnO_4^-/Mn^{+2}$ couple decreases by 0.377 from its standard value.
Hence (a) is the correct answer.
Help Clay6 to be free
Clay6 needs your help to survive. We have roughly 7 lakh students visiting us monthly. We want to keep our services free and improve with prompt help and advanced solutions by adding more teachers and infrastructure.

A small donation from you will help us reach that goal faster. Talk to your parents, teachers and school and spread the word about clay6. You can pay online or send a cheque.

Thanks for your support.
Continue
Please choose your payment mode to continue
Home Ask Homework Questions
Your payment for is successful.
Continue
Clay6 tutors use Telegram* chat app to help students with their questions and doubts.
Do you have the Telegram chat app installed?
Already installed Install now
*Telegram is a chat app like WhatsApp / Facebook Messenger / Skype.
...