Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: kmcclenn on October 12, 2017, 09:59:34 PM

Title: Electrochemical Cell
Post by: kmcclenn on October 12, 2017, 09:59:34 PM

 In an electrochemical cell with aluminum, Copper and a hydrochloric acid solution, what are the specific chemical reactions? I know that hydrogen gas is produced, but what is the substance that is plated on the copper?

Title: Re: Electrochemical Cell
Post by: Borek on October 13, 2017, 02:50:33 AM

Please read the forum rules (http://www.chemicalforums.com/index.php?topic=65859.0).

Have you checked reduction potentials?

Title: Re: Electrochemical Cell
Post by: Arkcon on October 13, 2017, 08:58:38 AM

Is there a reaction between components without an electrochemical cell?  If so, your answer will now be muddied by the completing reaction.

When describing an electrochemical cell, you have to specify which is the anode and cathode, or else you've described nothing at all.

Title: Re: Electrochemical Cell
Post by: kmcclenn on October 13, 2017, 09:12:28 PM

Copper is the anode, and aluminum is the cathode.

Title: Re: Electrochemical Cell
Post by: Arkcon on October 14, 2017, 06:53:32 AM

Good work.  Now.  Can you write redox half-reactions, using the electrons, for each electrode.  Also, are you aware of reactions that happen without added electrons, between electrode materials and the electrolyte of choice?  Don't ignore that.

I hope you don't mind my answering your questions, with other questions.  But that's what we do here.  We try to help you help yourself.  Its part of the Forum Rules{click} (http://www.chemicalforums.com/index.php?topic=65859.0). You already accepted them when you signed up for our forum, and they apply to you, whether you agree with them or not, or even if you're unaware of them.  Some of our newest members seem to have missed that point.

Title: Re: Electrochemical Cell
Post by: kmcclenn on October 15, 2017, 08:18:37 PM

When you put plain copper into plain hydrochloric acid, nothing happens. Aluminum reacts with hydrochloric acid, it produces aluminum chloride and hydrogen gas. For the electrochemical cell, the two half reactions are (I think):
2H+ + 2e- = H2
2Cl- + 2H2O + Cu+2 = 2H2 + CuCl2O2

Then, the copper gets more negative and the aluminum gets more positive so the electrons flow from the copper to the aluminum.
Is this all that happens?

Title: Re: Electrochemical Cell
Post by: Enthalpy on October 17, 2017, 09:20:11 AM

Hydrochloric acid corrodes aluminium without any current, so I wonder if such a cell is any feasible, and whether one has ever worked.
There are presently attempts to develop aluminium batteries, but using other electrolytes.