[OrganicZA]

The redox reaction where ethanol is oxidised to ethanal using dichromate in acidic conditions gives the following redox equation:

Cr₂O₇^2- + 3C₂H₅OH + 8H⁺  2Cr³⁺ + 3C₂H₄O + 7H₂O

According to the equation, 1 mol Cr₂O₇^2- reacts with 3 mol C₂H₅OH to produce 3 mol C₂H₄O So therefore using these stoichiometric relationships in actual practical synthesis should involve ethanol as the limiting reagent for example, so that the theoretical yeild of ethanal can be calculated: Example; 0.188 mol Sodium Dichromate with 0.550 mol ethanol with ratio of (1:2.9) (ethanol LR) therefore theoretical yield of 0.550 mol ethanal.

Is this the right procedure using the straight forward redox equation or do organic mechanisms exist that change the ratios of reactants and/or products? 

[Borek]

Stoichiometry is stoichiometry.

Problems start when there are possible side products, as they can use your reactants.

[Babcock_Hall]

As a purely practical matter, overoxidation to an acid is a possibility.  There are reagents and protocols designed to get around this sort of problem.