Quiz on Identifying Aldehydes and Ketones using 2,4-DNP

What is the chemical used to test for the presence of aldehydes and ketones?

• Fehling's solution

• Benedict's solution

• Tollens' reagent

• 2,4-dinitrophenylhydrazine

What is the common name for the solution of 2,4-DNP in methanol and sulfuric acid?

• Brady's reagent

• Schiff's reagent

• Lucas reagent

• Grignard reagent

What color precipitate indicates the presence of an aldehyde or ketone when using 2,4-DNP?

• Blue or green

• Red or purple

• Black or brown

• Yellow or orange

What is the base molecule of 2,4-dinitrophenylhydrazine?

• Hydrazine

• Benzene

• Phenol

• Aniline

Which positions on the benzene ring are the nitro groups located in 2,4-DNP?

• Two and four

• One and three

• Four and six

• Three and five

What is the purpose of determining the melting point of the precipitate formed with 2,4-DNP?

• To calculate the molecular weight

• To measure the acidity of the solution

• To determine the purity of the solvent

• To identify the specific aldehyde or ketone

What is the first step in identifying a specific aldehyde or ketone using 2,4-DNP?

• React the carbonyl compound with 2,4-DNP

• Measure the boiling point

• Add water to the solution

• Perform a titration

What is done to the yellow-orange solid to purify it after filtration?

• Mix with a base

• Heat it to a high temperature

• Re-dissolve in ethanol and recrystallize

• Add more sulfuric acid

Why might boiling point data be needed in addition to melting point data?

• To ensure the solution is acidic

• To confirm the color of the precipitate

• To verify the presence of water

• Several 2,4-DNP derivatives can have similar melting points

What is formed when 2,4-DNP reacts with an aldehyde or ketone?

• 2,4-dinitrophenylhydrazone derivative

• Aldehyde hydrate

• Ketone oxide

• Carbonyl chloride