State the reagents and conditions for the formation of an aldehyde, starting from a primary-alcohol.

Answer: Heat with acidified potassium dichromate (IV), distilling off the aldehyde as it forms.
Explanation: To form an aldehyde from an alcohol the alcohol group must be oxidised. To do this we use potassium dichromate (IV) acidified by dilute sulfuric acid. We also need to heat the reaction mixture to overcome the activation energy required for the reaction. However, we do not want to heat under reflux else the once the aldehyde is formed it will be oxidised further to form a carboxyllic acid. Instead, we distill off the aldehyde product as it is formed.