3. When a concentrated urea solution is stored, it slowly condenses to biuret and ammonia by the following elementary reaction 2NH2-CO-NH2 ) NH2-CO-NH-CO-NH2 + NH3 To study the rate of condensation, a sample of urea (Curea = 20 gmole/L) is stored at 100°C and, after 7 hr and 40 min, 1% of the urea has turned into biuret and ammonia. Find a rate um expression for this condensation reaction.