HCl - Covalent Bonding - Conductivity?

[sxld_cu]

According to ChemWiki (http://chemwiki.ucdavis.edu/Inorgan...p__1:_The_Alkali_Metals/Chemistry_of_Hydrogen)
H is a nonmetal
So HCl is a covalent compound (not an ionic) since it is composed of two metals
Why does it still conduct electricity? (I thought this was only characteristic of ionic compounds?)

---

Members don't see this ad.

 

[Medix450]

It dissociates into H3O+ and Cl- in water, and Cl- is considered a good electrolyte. I think the rule is that strong acids are considered good electrolytes, but maybe some one else can confirm this.

 

[sxld_cu]

Thanks for your reply 🙂
That reasoning makes sense; however, I had a question that said that HBr was a covalent compound too, and since HBr is also a strong acid, by that reasoning, it would also be a strong electrolyte and conduct electricity

 

[Medix450]

http://www.stolaf.edu/depts/chemistry/courses/toolkits/121/js/naming/elec.htm

It seems all strong acids are strong electrolytes, HBr included. Hopefully that site helps you.

 

[chojin01]

all strong acids and bases are strong electrolytes... anything that can fully dissociate into ions will be strong electrolytes

 

[NextStepTutor_1]

Exactly, as @chojin01 stated, any compound that can favorably and fully dissociate in water (releasing parts of the compound as ions) will be classified as a strong electrolyte. A strong electrolyte can conduct electricity.
Why does electricity need a compound to be dissociable in water?
Electricity needs charges in order to propagate - in fact, that pretty much definitional. Electricity can be thought of as the flow of energy via charged particles (think of protons and electrons)
So naturally, in order for their to be electricity, or conductance/propagation of electric current, there needs to be ions present. A fully dissociable species will provide these ions to the solution and thus the solution becomes electrolytic.

Strong bases and strong acids are fully dissociable in water - that, too, is definitional.

Cheers!


http://forums.studentdoctor.net/forums/next-step-mcat-tutor-office-hours.970/

 

[sxld_cu]

Hi! Thanks for taking the time to answer my questions!
Your explanation about electrolytes does make sense. Strong acids and bases dissociate almost completely and are electrolytes because they form ions that can conduct current.
However, my question is more about the definition of a covalent compound. By definition, a covalent compound is composed of nonmetals, and H and Cl are both nonmetals, making HCl a covalent compound. Covalent compounds, also by definition, don't conduct electricity. And that is where I find a contradiction. I hope that makes sense!

 

[chojin01]

there are no absolutes...HCl contains a covalent bond, but it still conducts electricity because it's a strong acid. Yes, it is a contradiction by your definition of a covalent compound, but that's just the way it is. In GENERAL, covalent compounds won't conduct electricity unless it's a strong acid or base

 

[sxld_cu]

Great, thanks for your help @chojin01
🙂