Prelaboratory Questions And Problems

1. Give three examples of cases where electrochemical techniques can, in principle, be utilized for the transformation and/or removal of pollutants.

2. If an electrochemically-active pollutant is to be oxidized and it has a standard potential of +0.50 V (vs the standard hydrogen electrode, SHE), which of the following potentials could, in principle, be applied to an electrode to efficiently achieve that operation?

a) -0.50 V, b) 0 V, c) + 0.50 V, d) + 1.00 V vs SHE. Explain.

*3. Formaldehyde is a well-known toxic organic substance frequently found as a vapor. It can be degraded into harmless products with electrogen-erated hydrogen peroxide either in acidic (with the aid of a catalyst, not shown below) or basic solutions according to the following equations, respectively:

Based only on stoichiometric arguments and assuming no side reactions, in which of the two cases is the current efficiency for formaldehyde destruction higher? (Note: Current efficiency can be defined as the charge employed for a given process divided by the total charge passed through the system).

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