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I have been given task to write possible reaction equations, determine oxidizer, reducer, write corresponding electron-equations and calculate electromotive force (I do not know if that is what you call it in English) of reactions:

  1. Iron reaction with diluted sulfuric acid

  2. Aluminium reaction with solution of sodium hydroxide

Could you be so kind and help me with this task?

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    $\begingroup$ This looks like it might be homework. We don't directly answer homework questions (certainly if no effort has been attempted). Have you tried searching the web with the reagents? $\endgroup$ – LDC3 May 26 '14 at 20:06
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    $\begingroup$ Welcome to Chemistry Stack Exchange! Please add what you have attempted towards solving the problem into the body of your question. For more information, see the site's homework policy for how to ask homework questions. You were lucky to receive an answer this time, but please adhere to this practice in the future. $\endgroup$ – jonsca May 26 '14 at 20:34
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The ionic equation for this reaction is:

$\ce{Fe + 2H+ ~(+\;SO4^2- ) -> Fe^2+ + H2 ~(+\;SO4^2- )}$

As two half-reactions, it is seen that the iron is oxidized:

$\ce{Fe -> Fe^2+ + 2e- }$

The reductant (iron) transfers electrons to hydrogen, and is thus itself oxidized.

And the hydrogen is reduced:

$\ce{2H+ + 2e- -> H2}$

The oxidant (hydrogen) removes electrons from iron, and is thus itself reduced.

To calculate the reduction potential you have to solve the following equation:

$\Delta E = E_\text{acceptor} - E_\text{donor} = E_{\ce{2H+/H2}}- E_{\ce{Fe/Fe^2+}}$

$\Delta E = 0\ \mathrm{V} - (-0.41\ \mathrm{V}) = 0.41\ \mathrm{V}$

The reactions runs voluntarily if $\Delta E > 0$.

You can do the same for b).

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