Question

The percentage of nitrogen content in urea is
A. $26%$
B. $36%$
C. $46%$
D. $56%$

Answer 1

Hint: Urea is used as an ideal nitrogen source for plants. It is a processed form of ammonia and is used as a fertilizer. The nitrogen content estimation in the urea fertilizer tells about its potential and amount of fertilizer to be used per hectare of field. The molecular formula of urea is \[N{{H}_{2}}CON{{H}_{2}}\]. The percent of nitrogen can be calculated by knowing the mass of nitrogen and the total mass of urea multiplied by 100.

Formula used: \[N \% =\dfrac{Mass(N)}{Mass(Urea)}\times 100\]

Complete answer: Urea is a rich source of nitrogen that is used as a fertilizer for plants. The plants require nitrogen to make DNA, RNA, and various other important molecules that are required for proper growth and reproduction. The nitrogen present in the fertilizer is first converted into ammonium or nitrate by the degradation process performed by soil microbes. After the degradation, the nitrogen is taken by the plants in ammonium form majorly. Using urea as fertilizer increases the growth rate of plants and leads to more yield in less time as urea is rich in nitrogen.
Now, let us calculate the amount of nitrogen present in urea.
The molecular formula of urea is \[N{{H}_{2}}CON{{H}_{2}}\].
The molecular weights of Nitrogen is, $N=14$, carbon is, $C=12$, oxygen is, $O=16$, and hydrogen is, $H=1$ respectively.
The formula for calculating total Nitrogen percent in urea is \[N%=\dfrac{Mass(N)}{Mass(Urea)}\times 100\]
Now, to calculate the total weight or mass of Nitrogen in urea, we need to multiply its molecular weight by the number of nitrogen molecules present in urea.
The molecular weight of Nitrogen, $N=14$. The number of molecules of nitrogen present in urea is 2. So, $14\times 2=28$.
To calculate the total weight or mass of the compound that is urea, we need to add the total molecular weights of each element present in it. So, the total weight for nitrogen is 28, for carbon is 12, for oxygen is 16, and for hydrogen is $1\times 4=4$.
Now, substituting all the values in the formula, we get $N \% = \dfrac{28}{28+12+16+4}\times 100$.
Solving for the substituted values, we will get $N \% = \dfrac{28}{60}\times 100=0.46\times 100=46%$.
Therefore, the right answer is option C.

Note: Urea is found as a natural component in the urine of animals and humans. It is the first organic compound that was made artificially. In 1828, Frederich Wohler created synthetic urea using a combination of potassium cyanate with ammonium sulfate. It is now produced commercially with ammonia and carbon dioxide. It is a water-soluble compound and is easily used as a fertilizer.