# Chemical Forums

• February 17, 2019, 01:49:37 PM
• Welcome, Guest

•

Pages: [1]   Go Down

### AuthorTopic: Redox tritation , potential calculation doubt  (Read 215 times) !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="https://platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() {var po = document.createElement("script"); po.type = "text/javascript"; po.async = true;po.src = "https://apis.google.com/js/plusone.js";var s = document.getElementsByTagName("script")[0]; s.parentNode.insertBefore(po, s);})();

0 Members and 1 Guest are viewing this topic.

• Full Member
• Mole Snacks: +0/-0
• Offline
• Posts: 126
##### Redox tritation , potential calculation doubt
« on: January 30, 2019, 08:57:47 AM »

I don't understand why the Potential E for the tritation of H3AsO3 with Ce4+ at Φ<1 (excess of H3AsO3)is:

E= E°(H3AsO4/H3AsO3) +(0.059/2)log {([H3AsO4][H+]2)/ [H3AsO4]}

At Φ<1 I can assume E(tritrand) >>E(tritrant). Here the tritand is H3AsO3 (H3AsO3---> H3AsO4)

So E= E cat-E anod ≈ -Eanod

So why my textbook says that the potential is:

E= E°(H3AsO4/H3AsO3) +(0.059/2)log {([H3AsO4][H+]2)/ [H3AsO4}

Or in other words E= E(H3AsO4-->H3AsO3)   (reduction potential)
Shouldn't be E = -E(H3AsO4--> H3AsO3),because H3AsO3/H3AsO4 is the anode!!?

??
Thanks!
Logged

#### Vidya

• Full Member
• Mole Snacks: +42/-60
• Offline
• Gender:
• Posts: 723
• Online Chemistry and Organic Chemistry tutor
##### Re: Redox tritation , potential calculation doubt
« Reply #1 on: February 03, 2019, 07:08:44 PM »

Or in other words E= E(H3AsO4-->H3AsO3)   (reduction potential)
Shouldn't be E = -E(H3AsO4--> H3AsO3),because H3AsO3/H3AsO4 is the anode!!?

??
Thanks!

yes it is oxidation and if reduction potential is given then you need to take reverse of it.
If the formula is Ecell = Ecathode + E anode
however is you are using this formula
Ecell = Ecathode - E anode
Then you need to take reduction potential as such as negative of the formula is making it oxidation potential.

Pages: [1]   Go Up

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.065 seconds with 23 queries.