Question

Calculate the percentage of nitrogen in urea $ \left( {{H_2}NCON{H_2}} \right) $
(A) $ 46.6\% {\text{ N}} $
(B) $ 43.6\% {\text{ N}} $
(C) $ 44.6\% {\text{ N}} $
(D) $ 42.6\% {\text{ N}} $

Answer 1

Hint: We need to first calculate the molecular weight of urea and the weight of nitrogen present in one mole of urea. Then using the basic percentage formula will give us the answer. To calculate a percentage of a percentage, convert both percentages to fractions of 100, or to decimals, and multiply them. We need nitrogen in urea so look for the overall contribution of the element in the urea formula.

Complete step by step answer
We need to calculate the percentage of nitrogen in urea.
Molecular weight of urea $ \left( {{H_2}NCON{H_2}} \right) = 4 + 28 + 12 + 16 = 60{\text{g}} $
Thus, we can say that:
60g of urea contains 28g of N
So, $ \% {\text{age of nitrogen}} = \dfrac{{28}}{{60}} \times 100 = 46.6\% $
So, we need to select the correct answer.
The correct answer is A.

Additional Information
Urea (also known as carbamide) is a waste product of many living organisms, and is the major organic component of human urine. This is because it is at the end of a chain of reactions which break down the amino acids that make up proteins. It forms in our body when dietary proteins make amino acids after digestion. The liver breaks down excess amino acids to make ammonia, then converts this into urea, which is less toxic in the body than ammonia.
Urea can be irritating to skin, eyes, and the respiratory tract in the human body. Repeated or prolonged contact with urea in fertilizer form on the skin may cause dermatitis. High concentrations in the blood can be damaging. So, urea has negative effects on the body.

Note
Urea is used to treat dry/rough skin conditions (e.g., eczema) and some nail problems (e.g., ingrown nails). It may also be used to help remove dead tissue in some wounds to help wound healing. Urea is known as a keratolytic. Urea is the most important nitrogenous fertilizer in the market, with the highest Nitrogen content (about 46 percent). It is a white crystalline organic chemical compound.