[maojaiyui]

Hello, I am having problem understanding the reduction and oxidation for electrochemistry section.  For example, one question of mine asks "Is H2(g) capable of reducing Ag+(aq)? (where a table of given standard condition reduction potentials are give)"  How should i approach in knowing that?

Thank you

[macman104]

Write the overall reaction of H2 reducing Ag+, and then the half-reactions first.

[maojaiyui]

example just for H2 reducing Ag+, please?

[enahs]

You have two equations.

You are asked if hydrogen gas can reduce Ag⁺.
So, get your two equations from your tables. Have Ag+ being reduced and Hydrogen gas being oxidized. Make sure to balance electrons. Add up the total voltage for the cell.
Is it positive or negative?
Which sign (+) or (-) indicates a spontaneous process?

[Borek]

My bet is that just looking at the reactivity series will do.

[maojaiyui]

it is spontaneous when the voltage is +  - and i get it now ty~

[enahs]

My bet is that just looking at the reactivity series will do.

Yes. But if your teacher gives you the question and the potentials, they are probably wanting you to demonstrate you understand the material!

[Borek]

Yes. But if your teacher gives you the question and the potentials, they are probably wanting you to demonstrate you understand the material!

Sure. Still, writing reaction equation and calculating potential of the cell is an overkill - it is enough to compare standard reduction potentials, which is in fact equivalent to using reactivity series. Question asks just whether H₂ is capable of reducing - what you propose is an overkill.

Just a humble opinion, I prefer to use as simple means of getting to the answer as possible

[enahs]

I agree that looking at the two values should be obvious, at least to us. But he/she has to start somewhere!

[maojaiyui]

Thank you for the help, so now I'm stuck on this problem -- Can't figure a way to start off

Chlorine dioxide (ClO2), which is produced by the reaction below, has been tested as a disinfectant for municipal water treatment.

2 NaClO2(aq) + Cl2(g) ----->   2 ClO2(g) + 2 NaCl(aq)

(a) Using data from Table 11.1, calculate script e°, ΔG°, and K at 25°C for the production of ClO2.

What should I do to start off on this problem?  [please don't state the answer]

[Astrokel]

Table 11.1?

[maojaiyui]

its a table reference for all the potential reduction (half reactions)

[Astrokel]

Maybe you would want to check this out: http://en.wikipedia.org/wiki/Gibbs_free_energy

Which equations are applicable?