thoroughly explain the following questions. 1. During the nitrogen test of urea, what happens to the nitrogen present in urea during the test that ultimately gives a positive result? Why does the nitrogen become detectable? 2. Urea is soluble in concentrated sulfuric acid. What interaction between urea and sulfuric acid could account for this solubility? 3. When urea was heated with NaOH, a gas was evolved that turned moist red litmus paper blue. What chemical reaction produced this gas? Write the reaction and explain why the litmus changed colour. 4. When urea is strongly heated, it produces biuret. What chemical change occurs during heating, and why is ammonia released? 5. After heating urea to form biuret, NaOH and CuSO were added and a violet colour appeared. What is responsible for the violet colour? Why is NaOH required? 6. Urea gave a negative Baeyer's test. What chemical reaction would have been responsible for a positive Baeyer's test, and why did it not occur with urea? 7. Urea did not produce effervescence with NaHCO,. Why? 8. The aromaticity test for urea was negative. What structural feature would have been necessary for a positive aromaticity test, and why is it absent in urea? Hint: Test Nitrogen test (+) What happened / did not happen Organic nitrogen was converted into a detectable chemical form, giving the characteristic positive reaction. Alkaline Urea hydrolyzed in strong alkali to produce NH,, which turned moist red litmus blue. hydrolysis (+) On heating, two urea molecules condensed to form biuret, which formed a violet Cu² complex in alkaline medium. Biuret (+) No readily oxidizable C=C/C=C unsaturation was present. Baeyer's (-) -COOH group was not present to liberate CO2. NaHCO, (-) Aromaticity (-) No aromatic ring was present.

Make a quick-reference PDF for these reactions

Glue much u can reply at a time

Make a one-page table of positive and negative observations