MDCAT Chemistry MCQ #291

A student reacts ethanal (44 g/mol) with 2,4-dinitrophenylhydrazine (198 g/mol). What is the molar mass of the resulting yellow-orange hydrazone precipitate?

MDCAT Chemistry MCQ #291

  1. Question 1

    Q1. A student reacts ethanal (44 g/mol) with 2,4-dinitrophenylhydrazine (198 g/mol). What is the molar mass of the resulting yellow-orange hydrazone precipitate?

    • A) 198 g/mol
    • B) 242 g/mol
    • C) 180 g/mol
    • D) 224 g/mol

    Answer: 224 g/mol

    Explanation: Acetaldehyde (44) + 2,4-DNP (198) - H2O (18) = 224. 242 is tempting as it fails to subtract the water molecule lost.