In this case, when a primary alcohol such as 1-butanol (OH is bonded to a primary carbon) is oxidized in the presence of a strong oxidizing media such as potassium dichromate (K2Cr2O7) and sulfuric acid, the stepwise oxidation goes to the corresponding aldehyde with a further oxidation to the corresponding carboxylic acid:
Therefore, on the attached picture you can find that the formed aldehyde is butanal and the inly organic product, due to the strong oxidizing media is finally butanoic acid.