Re: pinhole Burners and/or Torches

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From: Paul Doherty (pauld@exploratorium.edu)
Date: Thu Oct 17 2002 - 08:57:19 PDT 

Message-Id: <l0311071ab9d48db8927f@[192.174.3.125]>
Date: Thu, 17 Oct 2002 08:57:19 -0700
From: Paul Doherty <pauld@exploratorium.edu>
Subject: Re: pinhole Burners and/or Torches

The forces holding the sugar crystal together are London Dispersion forces
while the salt crystal is held together by ionic bonds.

On a scale where covalent bonds have a strength of 100 the London forces
have a strength of 0.001 to 0.1

So sugar melts at a lower temperature that covalently bonded solids (diamond)
Ionic bonds are closer to covalent in strength. So salt melts at a higher
temperature than sugar.

Paul D

>I want to
>1) melt sugar and salt in test tubes to demonstrate the difference in
>strength of ionic and covalent bonds.
>2) burn pennies to show the difference between zinc and copper.
>
>However, my school does not have gas lines or portable burners that I
>can access.
>
>So my questions are
>1) Will a portable propane/bunsen burner do for both needs? A
>previous teacher mentioned using a "torch" for the pennies.
>2) Does anyone know where I can find one easily and inexpensively,
>preferably in the east bay?
>
>Thanks, from a new-to-physical-science-and-urban-school teacher,
>Charlotte
>
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