Ethanal can be by oxidation of ethanol, as shown below:
CH3CH2OH + [O] ↔ CH3CHO + H2
Above reaction is exothermic in nature, hence later amount of heat is released during the course of reaction.
Now, Le Chatelier's principle is stated as 'any changes in the temperature, volume, or concentration of a system will result in predictable and opposing changes in the system in order minimize this change and achieve a new equilibrium state.'
Thus, the yield of product can be enhanced by following two ways:
1) Increasing the concentration of reactant i.e. CH3CH2OH. Due to this, equibrium will shift to right and hence, favor the formation of product.
2) Decreasing the temperature of system. Since, the reaction is exoothermic in nature, according to Le Chatelier's principle, lowering the temperature of system will shift the equibrium will shift to right and hence, favor the formation of product.
Thus, concentration of reactant and temperature of system will influence the equilibrium to produce more ethanal.