Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: pcm81 on January 12, 2018, 05:50:42 PM

Title: Acid reactivity vs metals chart
Post by: pcm81 on January 12, 2018, 05:50:42 PM
Hi. It's been about 15 years since my last college chemistry class and i can't remember the name of the property i am looking for to find it online. As I recall there is more to acids reacting with metals than acid disassociation constant characterizing acid strength... After all a strong sulphuric acid cant dissolve gold, but HCL + Nitric mixture can. What is the name of the propetry i am looking for that will tell me which acids can and cannot dissolve which metals. I think it has something to do with nobilty of metals too...



Thanks ahead.
Title: Re: Acid reactivity vs metals chart
Post by: Borek on January 12, 2018, 06:03:29 PM
I don't think there is a single term covering what you are looking for. Some metals need strong oxidizers to dissolve. H+ is an oxidizer, but not strong enough. In general it is about redox potentials, but as a rule of thumb you can use reactivity series.

Hopefully some of these keywords will ring a bell for you.
Title: Re: Acid reactivity vs metals chart
Post by: pcm81 on January 12, 2018, 10:54:07 PM
I don't think there is a single term covering what you are looking for. Some metals need strong oxidizers to dissolve. H+ is an oxidizer, but not strong enough. In general it is about redox potentials, but as a rule of thumb you can use reactivity series.

Hopefully some of these keywords will ring a bell for you.

If my memory serves me right it has something to do with oxidation reduction potential like in this chart:
http://eesemi.com/ox_potential.htm

Which is why HF pretty much dissolves everything since F has such much high potential.
Just was not sure if there is a table for acids vs metals allowing me not to think...
Title: Re: Acid reactivity vs metals chart
Post by: Borek on January 13, 2018, 04:06:10 AM
If my memory serves me right it has something to do with oxidation reduction potential like in this chart:

Yes.

Quote
Which is why HF pretty much dissolves everything since F has such much high potential.

No. It is elemental fluorine (F2) that is a strong oxidizer, in HF fluorine is in a form of fluoride anion (F-), which is already reduced and not that reactive. Yes, it still has some interesting properties.
Title: Re: Acid reactivity vs metals chart
Post by: Enthalpy on January 14, 2018, 08:05:03 PM
The corrosion resistance of metals does not depend simply on a redox potential. It depends much on the quality of the surface oxide.

For instance Ta resists corrosion very well but isn't a noble metal.

Or Cr makes steel stainless despite its redox potentials are similar to Fe.