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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: IBM on October 04, 2018, 01:20:28 PM

Title: Which compound is oxidized and which one reduced in the reaction below?
Post by: IBM on October 04, 2018, 01:20:28 PM

Which compound is oxidized and which one reduced in the reaction below?
H3PO3 = H3PO4 + PH3

Title: Re: Which compound is oxidized and which one reduced in the reaction below?
Post by: Babcock_Hall on October 04, 2018, 01:32:52 PM

Assign oxidation numbers to the atoms.

Title: Re: Which compound is oxidized and which one reduced in the reaction below?
Post by: IBM on October 05, 2018, 11:37:25 AM

Quote from: Babcock_Hall on October 04, 2018, 01:32:52 PM

Assign oxidation numbers to the atoms.

H3PO3 (P =+3) = H3PO4 (P =+5) + PH3 (P= -3)

Title: Re: Which compound is oxidized and which one reduced in the reaction below?
Post by: Babcock_Hall on October 05, 2018, 12:28:28 PM

That looks OK to me.

Title: Re: Which compound is oxidized and which one reduced in the reaction below?
Post by: IBM on October 06, 2018, 02:30:29 AM

Quote from: Babcock_Hall on October 05, 2018, 12:28:28 PM

That looks OK to me.

H3PO3 (P =+3) = H3PO4 (P =+5) + PH3 (P= -3)
Could you tell me now which compound is reduced and which compound is oxidized here?

Title: Re: Which compound is oxidized and which one reduced in the reaction below?
Post by: chenbeier on October 06, 2018, 03:25:49 AM

Learn definition of oxidation: Oxidation is a release of electrons. What does it mean for the oxidation number? Reduction is a acception of electrons, what does it means for the oxidations number?

Title: Re: Which compound is oxidized and which one reduced in the reaction below?
Post by: mjc123 on October 08, 2018, 04:50:47 AM

This is not a standard redox reaction, with an oxidising agent and a reducing agent. It is what is called a disproportionation, in which some of the starting material is oxidised and some is reduced. You start with all P(+3), some of it is oxidised to P(+5) and some reduced to P(-3).
By the way, you should try balancing your equation. Not only the numbers of atoms, but also the oxidation numbers, should balance.