Re: pinhole Plating zinc onto a penny with sodium hydroxide

Date view Thread view Subject view Author view Attachment view

From: Marc Crown (mcrown@gwhs.org)
Date: Tue Dec 14 2004 - 08:23:28 PST 

Message-Id: <7C7FD146-4DEC-11D9-A6C5-000A95AE197E@gwhs.org>
From: Marc Crown <mcrown@gwhs.org>
Subject: Re: pinhole Plating zinc onto a penny with sodium hydroxide
Date: Tue, 14 Dec 2004 08:23:28 -0800

Geoff, I would love to see a copy of this article
thanks
marc

On Dec 14, 2004, at 7:25 AM, Geoff Ruth wrote:

> Some people at Saturday's Chemapolooza were curious about the
> reactions when you heat up 6M sodium hydroxide + Zn to plate zinc onto
> a penny.
>
> First, the "zincate" ion is created: [Zn(OH)4]-2
>
> This ion is then reduced to zinc metal at the surface of the penny.
> The reducing agent is incorrectly reported on many web sites as being
> copper or water, which doesn't make sense since pH is constant
> throughout and since there is no color change (with Cu2+ being
> formed).
>
> According to the following interesting article in J Chemical
> Education, the oxidation of zinc (at the Zn metal) itself provides the
> e- needed to reduce the zinc back at the penny:
>
> Volume 72 Issue 5 / May 1995
> Szczepankiewicz, Steven H.; Bieron, Joseph F.; Koz
> The "Golden Penny" Demonstration: An Explanation of the Old Experiment
> and the Rational Design of the New and Simpler Demonstration,   pp.
> 386-388
>
>
> If anyone wants, I can e-mail or mail the actual JCE article.
>
> - Geoff Ruth

Date view Thread view Subject view Author view Attachment view

This archive was generated by hypermail 2.1.3 : Mon Aug 01 2005 - 16:06:45 PDT