Simple Chemistry: Nitric Acid

1. May 27, 2007

ritwik06

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

2. May 27, 2007

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

3. May 28, 2007

ritwik06

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

4. May 29, 2007

chemisttree

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

5. May 29, 2007

Stevedye56

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

6. May 30, 2007

ritwik06

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

7. Jun 2, 2007

ritwik06

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?????

8. Jun 3, 2007

chemisttree

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

9. Jun 3, 2007

ritwik06

I dont know. I cant make out what you are talking about.

10. Jun 3, 2007

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...

11. Jun 3, 2007

f(x)

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.

12. Jun 5, 2007

ritwik06

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

13. Jun 5, 2007

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.

14. Jun 5, 2007

ritwik06

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???

15. Jun 5, 2007

chemisttree

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.