Nitric Acid: Understanding its Oxidizing Properties on Dilution

[ritwik06]

Why does oxidizing nature of nitric acid gets reduced on dilution?

 

[f(x)]

When the acid is diluted, the volume over which H+ ions disperse get a larger volume, hence per unit volume, the oxidizing nature decreases

 

[ritwik06]

H+ ions are responsible for reducing nature, so why oxidizing nature decreases?

 

[chemisttree]

Why does oxidizing nature of nitric acid gets reduced on dilution?

What do you mean by 'oxidizing nature'? Rate of oxidation?

 

[Stevedye56]

Do you mean why is a subastance being oxidized the reducing agent?

 

[ritwik06]

What do you mean by 'oxidizing nature'? Rate of oxidation?

Do you mean why is a subastance being oxidized the reducing agent?

I am sorry! I got it. Thanks a lot to all of you!

 

[ritwik06]

I am sorry! I got it. Thanks a lot to all of you!

I was muddled. Nitric acid dissociates to give H+ ions. right? but additon of H+ to something ould lead to reduction. But nitric acid is actually an oxidizing agent. how come?

 

[chemisttree]

What is the oxidation # for nitrogen in the nitrate ion? Is it unusual?

 

[ritwik06]

What is the oxidation # for nitrogen in the nitrate ion? Is it unusual?

I don't know. I can't make out what you are talking about.

 

[chemisttree]

Oxygen usually has an oxidation number (I'll call it a 'charge') of -2. There are three of them (oxygens in nitrate) and there is one negative charge left over. What is the charge on nitrogen required to balance all but one of these negative charges?

Nitrogen usually has an oxidation number of -3...

 

[f(x)]

H+ ions are responsible for reducing nature, so why oxidizing nature decreases?

no, H+ itself gets reduced while the other substance loses e- and gets oxidized
. As $HNO_3$ is diluted, it loses oxidizing tendency and behaves more as an acid.

 

[ritwik06]

Oxygen usually has an oxidation number (I'll call it a 'charge') of -2. There are three of them (oxygens in nitrate) and there is one negative charge left over. What is the charge on nitrogen required to balance all but one of these negative charges?

Nitrogen usually has an oxidation number of -3...

The charge of Nitrogen should be +5. Yes, nitride ion has charge -3. So what do I deduce from this?

 

[chemisttree]

The oxidative property of nitric acid comes from the nitrate ion. The proton doesn't counteract this at all. I don't know of any reactions where H+ is a reducing agent or where it could lead to reduction.

 

[ritwik06]

The oxidative property of nitric acid comes from the nitrate ion. The proton doesn't counteract this at all. I don't know of any reactions where H+ is a reducing agent or where it could lead to reduction.

I think you are true, the oxidation property comes from the nitrate ion. And moreover we arent talking about H+ ions' "reducing" property.

But sir, please do tell me that when nitrogen in nitrate has oxidation # +5, then how does it effect the oxidizing nature?

 

[chemisttree]

...But sir, please do tell me that when nitrogen in nitrate has oxidation # +5, then how does it effect the oxidizing nature?

Any atom at a high oxidation state can behave as an oxidant. Normally nitrogen has a -3 oxidation state. In nitrate it is +5. Thats EIGHT ELECTRONS higher than it normally occurs. Any atom that is capable of lowering its oxidation state by eight electrons is DEFINITELY an oxidant. In gunpowder, KNO3 is the oxidant. The nitrogen-containing product is N2. That is a 5 electron change which is still a pretty stout oxidation.

Dilution doesn't change that. It slows it down.