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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: crazy4laptops on September 23, 2007, 03:32:07 PM

Title: mg & S questions
Post by: crazy4laptops on September 23, 2007, 03:32:07 PM

Does magnesium burn underwater?

I tried lighting sulfur powder with a match, it just melted, it didn't burn. What needs to be done in order to get sulfur to burn?

Title: Re: mg & S questions
Post by: DevaDevil on September 25, 2007, 04:16:01 PM

Mg --> Mg²⁺ + 2e^-   E=2.38V
O₂ + 2H₂O + 4e^-  --> 4OH^-  E= 0.40V
or if you de-oxygenate the water first (protons supplied by the water equilibrium):
2H⁺ + 2e^- --> H₂  E = 0V

what do you think would happen if you get pure magnesium in contact with water?


Burning sulfur can be achieved in pure oxygen - the content in air is too low.

See here (http://www.angelo.edu/faculty/kboudrea/demos/burning_sulfur/burning_sulfur.htm) for a good example. If you want to try this BE SAFE, working with flammables and pure oxygen is very hazardous. And the fumes are dangerous (think of the origin of acid rain), the create strong acids on contact with water.

Title: Re: mg & S questions
Post by: Sam (NG) on September 26, 2007, 04:59:28 AM

I'm seen sulfur burnt in air in the lab when i was in 6th grade, just used a bunsen burner to ignite it first.  Theoretically from a safety point of view, our teacher was a moron he should have at least had the windows open when we did the experiment.