Urea Formula: CH4N2O – Molecular Mass, Structure & Solved Examples

What Is Urea?

Urea is an organic compound that serves as the primary nitrogen-containing waste product of protein metabolism in mammals. It is excreted in urine, making it a key compound in biochemistry and renal physiology.

In industry, urea is the world’s most widely used nitrogen-based fertilizer, supplying 46% nitrogen by weight. It is also used in plastics, resins, animal feed supplements, and medical diagnostics.

Identity Facts About Urea:

• Also known as: Carbamide
• Discovered by: Friedrich Wohler (1828) first organic compound synthesized from inorganic materials
• Physical form: White crystalline solid at room temperature
• Taste: Slightly salty
• Solubility: Highly soluble in water
• State at Room Temperature: Solid

Urea Formula

The Chemical Formula of Urea:

CH4N2O (also written as CO(NH2)2 or H2NCONH2 or (NH2)2CO)

The formula CH4N2O tells us the exact number of each type of atom present in one molecule of urea:

Element	Symbol	Number of Atoms	Atomic Mass (g/mol)	Total Mass Contribution
Carbon	C	1	12.011	12.011
Hydrogen	H	4	1.008	4.032
Nitrogen	N	2	14.007	28.014
Oxygen	O	1	15.999	15.999
TOTAL	—	8 atoms	—	60.056 g/mol

The formula CO(NH2)2 is the expanded or functional form that shows the two amino groups (NH2) attached to a carbonyl group (C=O). Both notations represent the same compound.

Urea Formula Name (IUPAC & Common Names)

Name Type	Name	Context of Use
IUPAC Name	Carbonamide (or Diaminomethanone)	Formal chemistry, research papers
Common Name	Urea	Everyday chemistry, exams, textbooks
Alternative Common Name	Carbamide	Pharmaceutical, biochemistry contexts
Systematic Name	Diaminoformaldehyde	Older literature
Biochemistry Name	Urea (end product of urea cycle)	Biology, physiology, nephrology

The IUPAC name carbonamide and the common name urea are both accepted. Most Indian board exams and competitive exams use the name urea with the formula CH4N2O or CO(NH2)2.

Urea Molecular Formula

What the Molecular Formula

The molecular formula CH4N2O reveals:

• C = 1 carbon atom in the molecule
• H = 4 hydrogen atoms (2 from each NH2 group)
• N = 2 nitrogen atoms (one in each amino group)
• O = 1 oxygen atom (in the carbonyl group C=O)

Empirical Formula vs. Molecular Formula of Urea

Formula Type	Formula	Meaning
Molecular Formula	CH4N2O	Exact number of each atom per molecule
Empirical Formula	CH4N2O	Simplest whole-number ratio (same as molecular for urea)
Structural Formula	H2N-CO-NH2	Shows how atoms are bonded
Condensed Formula	CO(NH2)2	Shows functional groups clearly
Lewis Structure Formula	(NH2)2C=O	Shows bonding and lone pairs

Important Note:

For urea, the empirical formula and molecular formula are the SAME — CH4N2O — because the ratio of atoms C:H:N:O = 1:4:2:1 is already in its simplest form and cannot be reduced further.

Urea Structural Formula & Lewis Structure

Structural Formula of Urea

Structural Formula of Urea

O = H2N — C — NH2

(carbonyl carbon bonded to two amino groups)

Explanation of Urea’s Structure

• Central Carbon Atom: sp2 hybridized, forms 3 sigma bonds
• Carbonyl Group (C=O): A double bond between carbon and oxygen this is the defining feature
• Two Amino Groups (NH2): Each nitrogen has 2 hydrogen atoms and one lone pair
• Bond Angles: Approximately 120 degrees around the central carbon (trigonal planar geometry)
• Resonance: Urea exhibits resonance; the C-N bonds have partial double bond character

Geometry & Hybridization

Feature	Detail
Geometry	Trigonal planar around central carbon
Hybridization of C	sp2
Hybridization of N	sp3 (but with partial sp2 due to resonance)
Bond Angle (N-C-N)	~116 degrees
Bond Angle (N-C-O)	~122 degrees
C=O Bond Length	1.26 A (shorter than typical C-O, longer than pure C=O due to resonance)
C-N Bond Length	1.34 A (shorter than typical C-N, showing partial double bond character)

Step-by-Step Calculation of Urea Formula Molecular Mass

What Is Molecular Mass?

Molecular mass is the sum of the atomic masses of all atoms in one molecule of a compound. It is expressed in atomic mass units (amu) or grams per mole (g/mol).

Formula for Molecular Mass:

Molecular Mass = Sum of (Number of each atom x Atomic mass of that atom)

Step-by-Step Calculation of Molecular Mass of Urea (CH4N2O)

Step	Element	No. of Atoms	Atomic Mass (amu)	Calculation	Result (amu)
1	Carbon (C)	1	12.011	1 x 12.011	12.011
2	Hydrogen (H)	4	1.008	4 x 1.008	4.032
3	Nitrogen (N)	2	14.007	2 x 14.007	28.014
4	Oxygen (O)	1	15.999	1 x 15.999	15.999
TOTAL	—	8	—	Sum of all	60.056 g/mol

Molecular Mass of Urea:

60.056 g/mol (commonly rounded to 60.06 g/mol or simply 60 g/mol in board exams)

Molar Mass vs. Molecular Mass

• Molecular Mass: Mass of one molecule of urea = 60.056 amu
• Molar Mass: Mass of one mole (6.022 x 10^23 molecules) of urea = 60.056 g/mol
• For exam purposes: The numerical values are identical; only the units differ (amu vs g/mol)

Complete Formula Table

This section provides every formula related to urea that appears in school and competitive examinations.

A. Identity & Composition Formulas

Formula Name	Formula	Explanation	Variables	Exam Use Case
Molecular Formula	CH4N2O	Exact atomic composition of one urea molecule	C, H, N, O atoms	Write the formula of urea
Alternative Molecular Formula	CO(NH2)2	Highlights carbonyl + 2 amino groups	Functional groups	Show functional groups in urea
Expanded Formula	H2N-CO-NH2	Shows connectivity of all atoms	All atoms and bonds	Draw structural formula
Empirical Formula	CH4N2O	Simplest atom ratio (same as molecular)	Whole number ratio	Empirical vs molecular formula Qs
Molecular Mass Formula	M = 12+4+28+16 = 60	Sum of atomic masses (rounded values)	Atomic masses of C,H,N,O	Calculate molecular mass

B. Mole Concept Formulas Applied to Urea

Formula Name	Formula	Explanation	Example with Urea
Number of Moles	n = mass (g) / molar mass (g/mol)	Calculate moles from given mass	n = 120 / 60 = 2 moles of urea
Mass from Moles	mass = n x M	Find mass when moles are given	mass = 3 x 60 = 180 g of urea
Number of Molecules	N = n x 6.022 x 10^23	Avogadro’s number application	1 mol urea = 6.022 x 10^23 molecules
Number of Atoms	Atoms = N x atoms per molecule	Total atoms in sample	1 mol urea has 8 x 6.022 x 10^23 atoms
Number of N atoms	N(N) = n x 2 x 6.022 x 10^23	Urea has 2 N atoms per molecule	1 mol urea = 1.204 x 10^24 N atoms

C. Percentage Composition Formulas

Element	Formula for % Composition	Calculation	Result
% Carbon	(12/60) x 100	12.011/60.056 x 100	20.00%
% Hydrogen	(4/60) x 100	4.032/60.056 x 100	6.71%
% Nitrogen	(28/60) x 100	28.014/60.056 x 100	46.65%
% Oxygen	(16/60) x 100	15.999/60.056 x 100	26.64%
Total	—	Sum must equal 100%	100.00%

Agricultural Significance: Nitrogen content of urea = 46.65% This is WHY urea is the most popular nitrogen fertilizer. No other solid nitrogen fertilizer provides as high a nitrogen percentage.

D. Synthesis & Reaction Formulas

Reaction Name	Chemical Equation	Conditions	Significance
Wohler Synthesis (1828)	NH4CNO –heat–> (NH2)2CO	Heat	First lab synthesis of organic from inorganic compound
Industrial Synthesis (Bosch-Meiser)	CO2 + 2NH3 –> (NH2)2CO + H2O	150-200 atm, 180-200 degC	Commercial urea production
Step 1: Carbamate Formation	CO2 + 2NH3 –> NH4COONH2	High pressure	Exothermic intermediate step
Step 2: Dehydration	NH4COONH2 –> (NH2)2CO + H2O	High temp, low pressure	Endothermic dehydration step
Biuret Formation (side reaction)	2(NH2)2CO –> NH(CONH2)2 + NH3	Excess heat	Undesirable impurity in fertilizer
Hydrolysis of Urea	(NH2)2CO + H2O –> CO2 + 2NH3	Urease enzyme or heat	Biological breakdown in soil

E. Physical Properties Formulas & Data

Property	Formula / Value	Notes
Solubility in Water	1080 g/L at 20 degC	Highly soluble; increases with temperature
Solubility Product	Not applicable (highly soluble)	No Ksp for urea
Melting Point	132.7 degC (405.85 K)	Decomposes above melting point
Density	1.323 g/cm3	At room temperature
pKa (conjugate acid)	~0.18	Very weak base
Degree of Unsaturation (DoU)	DoU = (2C + 2 + N – H) / 2 = (2 + 2 + 2 – 4) / 2 = 1	1 degree = one C=O double bond

Urea Synthesis Formula (Wohler & Industrial)

Wohler Synthesis

In 1828, Friedrich Wohler accidentally synthesized urea by heating ammonium cyanate. This event shattered the “vital force” theory which claimed organic compounds could only be produced by living organisms.

Wohler Synthesis Reaction:

NH4CNO –(heat)–> CO(NH2)2Ammonium Cyanate –> UreaKey: Ammonium cyanate (inorganic) converted to urea (organic) a milestone in chemistry history.

Industrial Production — Bosch-Meiser Process

Modern urea is produced industrially from ammonia and carbon dioxide. This is a two-step process:

Step 1 — Carbamate Formation (Exothermic):

CO2 + 2 NH3 –> NH2COONH4 (Ammonium Carbamate)

Conditions: 150-200 atm pressure, temperature around 180-200 degrees C

Step 2 — Dehydration (Endothermic):

NH2COONH4 –> (NH2)2CO + H2O

Conditions: Reduced pressure, high temperature drives water out

Overall Balanced Equation:

CO2 + 2 NH3 –> (NH2)2CO + H2O

Parameter	Value / Detail
Temperature	180-200 degrees C
Pressure	150-200 atm
Conversion Efficiency	~70-80% per pass
Raw Materials	Ammonia (NH3) and Carbon Dioxide (CO2)
By-product	Water (H2O)
Global Production	Over 180 million metric tons per year

Urea-Related Derived Formulas

A. Mole Concept — Formulas with Urea Examples

Concept	Formula	Example with Urea (M = 60 g/mol)
Moles from mass	n = W / M	n = 180 g / 60 g/mol = 3 mol
Mass from moles	W = n x M	W = 2.5 x 60 = 150 g
Molecules from moles	N = n x NA	3 mol x 6.022E23 = 1.807E24 molecules
Moles from molecules	n = N / NA	1.204E24 / 6.022E23 = 2 mol
Mass from molecules	W = (N / NA) x M	(1.204E24 / 6.022E23) x 60 = 120 g
Atoms of N from moles of urea	N(N-atoms) = n x 2 x NA	1 mol x 2 x 6.022E23 = 1.204E24 N atoms

B. Percentage Composition Formula

General Formula:

% of element = (Mass of element in formula / Molecular mass of compound) x 100For % Nitrogen in Urea:% N = (28 / 60) x 100 = 46.67%

C. Degree of Unsaturation (DBE) Formula

Degree of Unsaturation (DoU) or Double Bond Equivalent (DBE) indicates the number of rings or double bonds in a molecule.

DBE Formula for CnHmNpOq:

DoU = (2C + 2 + N – H) / 2For Urea CH4N2O:DoU = (2(1) + 2 + 2 – 4) / 2DoU = (2 + 2 + 2 – 4) / 2DoU = 2/2 = 1Result: 1 degree of unsaturation = the C=O double bond

D. Fertilizer-Related Formulas

Formula	Application	Urea Example
% N = (Total N mass / Formula mass) x 100	Calculating nitrogen content of fertilizer	% N = 28/60 x 100 = 46.67%
kg N per bag = (% N / 100) x bag mass (kg)	Finding actual N in a fertilizer bag	50 kg bag: 46.67/100 x 50 = 23.33 kg N
Fertilizer dose = (Crop N need / % N) x 100	Calculating how much fertilizer to apply	If 50 kg N needed: 50 / 0.4667 = 107 kg urea

Solved Examples

Question: Find the molecular mass of urea given its formula CH4N2O.

Solution:

• Molecular formula of urea = CH4N2O
• Atomic mass of C = 12, H = 1, N = 14, O = 16 (using rounded values for board exams)
• Molecular mass = 1(12) + 4(1) + 2(14) + 1(16)
• = 12 + 4 + 28 + 16
• = 60 g/mol

Answer:

Molecular mass of urea = 60 g/mol

Question: Calculate the number of moles in 120 g of urea.

Solution:

• Given: mass (W) = 120 g
• Molar mass of urea (M) = 60 g/mol
• Formula: n = W / M
• n = 120 / 60
• n = 2 moles

Answer:

120 g of urea = 2 moles of urea

Question: Find the percentage composition of nitrogen in urea CH4N2O.

Solution:

• Molecular formula = CH4N2O, Molecular mass = 60 g/mol
• Mass of N in one molecule = 2 x 14 = 28 g/mol
• % N = (mass of N / molecular mass) x 100
• % N = (28 / 60) x 100
• % N = 46.67%

Answer:

Nitrogen content in urea = 46.67% (This is why urea is valued as a fertilizer — it provides the highest % N of any solid nitrogenous fertilizer)

Question: Calculate the number of urea molecules in 30 g of urea.

Solution:

• Molar mass of urea = 60 g/mol
• Step 1: Find moles: n = 30 / 60 = 0.5 mol
• Step 2: Number of molecules = n x Avogadro’s number
• N = 0.5 x 6.022 x 10^23
• N = 3.011 x 10^23 molecules

Answer:

30 g of urea contains 3.011 x 10^23 molecules

Question: How many nitrogen atoms are present in 60 g of urea?

Solution:

• Molar mass of urea = 60 g/mol
• Moles of urea = 60/60 = 1 mol
• Each molecule of urea has 2 N atoms
• Moles of N atoms = 1 x 2 = 2 mol
• Number of N atoms = 2 x 6.022 x 10^23 = 1.204 x 10^24 atoms

Answer:

1.204 x 10^24 nitrogen atoms are present in 60 g of urea

Question: How many grams of ammonia (NH3) are needed to produce 60 g of urea? Use: CO2 + 2NH3 –> (NH2)2CO + H2O

Solution:

• Molar mass of urea = 60 g/mol, molar mass of NH3 = 17 g/mol
• Moles of urea to be produced = 60/60 = 1 mol
• From equation: 2 mol NH3 produces 1 mol urea
• Moles of NH3 needed = 2 x 1 = 2 mol
• Mass of NH3 = 2 x 17 = 34 g

Answer:

34 g of ammonia is required to produce 60 g of urea

Common Student Mistakes and How to Avoid Them

Mistake	Incorrect	Correct	Tip to Remember
Wrong atom count for H	Writing CH2N2O (only 2 H)	CH4N2O (4 H atoms total — 2 per NH2 group)	Two NH2 groups = 2 x 2 = 4 H atoms
Swapping N and O count	Writing CH4NO2	CH4N2O (2 N, 1 O)	Nitrogen is 2, Oxygen is 1 — N comes before O in the formula
Wrong molecular mass	Calculating as 56 or 64	60 g/mol	Always: 12 + 4 + 28 + 16 = 60
Confusing urea with uric acid	Using C5H4N4O3 for urea	CH4N2O for urea	Urea is simple (60 g/mol); uric acid is complex (168 g/mol)
Wrong IUPAC name	Calling it carbonate or carbamate	Carbonamide or diaminomethanone	The -amide suffix indicates NH2 groups on C=O
Using wrong atomic masses	Using N = 13 or O = 18	N = 14, O = 16	Memorize: H=1, C=12, N=14, O=16, S=32
Wrong % N calculation	% N = 14/60 x 100 = 23.3%	% N = 28/60 x 100 = 46.67%	There are TWO nitrogen atoms, so mass = 2 x 14 = 28

Memory Tricks & Exam Tips

Trick 1: Remember CH4N2O Using a Mnemonic

Mnemonic for CH4N2O:

Carbon Has 4 Neighbors, 2 Nitrogens, 1 Oxygen”C = 1 CarbonH = 4 HydrogensN = 2 NitrogensO = 1 Oxygen

Trick 2: The 60 Rule

The molecular mass of urea is exactly 60 g/mol using rounded atomic masses:

• 12 + 4 + 28 + 16 = 60
• Think: 12-4-28-16 adds up to 60. It is clean and round — easy to remember.

Trick 3: Functional Group Visualization

Picture urea as: Two hands (NH2) shaking around a double-bonded C=O center. That image gives you H2N-CO-NH2 = CO(NH2)2.

Trick 4: The 46% N Fertilizer Rule

Urea = 46% N. This number appears in agriculture questions. Remember: “4-6” as in 46 percent the highest N fertilizer available commercially.

Exam Strategy Tips

• Always write the formula as CH4N2O or CO(NH2)2 — both are accepted in CBSE, ICSE, and competitive exams
• In stoichiometry problems, use molar mass = 60 g/mol unless asked to use precise atomic masses
• In biological/biochemical questions, note that urea is the end product of the urea cycle (ornithine cycle) in mammals
• In agriculture questions, remember that urea provides 46.65% N the highest of any solid nitrogen fertilizer
• When writing the structural formula in organic chemistry, always show the C=O double bond clearly

FAQs About Urea Formula

Q. What is the chemical formula of urea?

The chemical formula of urea is CH4N2O, also written as CO(NH2)2. It contains 1 carbon, 4 hydrogen, 2 nitrogen, and 1 oxygen atom. The IUPAC name is carbonamide. Urea has a molecular mass of 60 g/mol.

Q. What is the molecular formula of urea and its molecular mass?

The molecular formula of urea is CH4N2O. Its molecular mass is 60.06 g/mol (commonly rounded to 60 g/mol). Calculated as: 1(12) + 4(1) + 2(14) + 1(16) = 60 g/mol. This is one of the most commonly asked values in board exams.

Q. What is urea ka formula?

Urea ka formula hai CH4N2O ya CO(NH2)2. Iska molecular mass 60 g/mol hai. Ismein 1 carbon, 4 hydrogen, 2 nitrogen, aur 1 oxygen atom hote hain. IUPAC naam carbonamide hai. Yaha formula CBSE aur state board dono exams ke liye same hai.

Q. What is the IUPAC name of urea?

The IUPAC name of urea is carbonamide. It is also called diaminomethanone in systematic nomenclature. The common name is urea, and it is also known as carbamide in pharmaceutical contexts. All three names refer to the same compound with formula CH4N2O.

Q. What is the structural formula of urea?

The structural formula of urea is H2N-CO-NH2, showing a central carbonyl group (C=O) flanked by two amino groups (NH2). It can also be written as (NH2)2CO or CO(NH2)2. The central carbon is sp2 hybridized, and the molecule has trigonal planar geometry.

Q. How do you calculate the molecular mass of urea?

Use the formula: Molecular mass = sum of (number of atoms x atomic mass) for each element. For urea CH4N2O: C=12, H=4×1=4, N=2×14=28, O=16. Total = 12+4+28+16 = 60 g/mol. Always use rounded atomic masses (H=1, C=12, N=14, O=16) in board exam calculations.

Q. What is the percentage of nitrogen in urea?

The percentage of nitrogen in urea is 46.67%. Calculated as: % N = (mass of N / molecular mass) x 100 = (28/60) x 100 = 46.67%. This is the highest nitrogen content of any solid nitrogen fertilizer, which is why urea is the most widely used agricultural fertilizer worldwide.

Q. Is urea organic or inorganic? Why is this important?

Urea is an organic compound because it contains carbon and is produced by living organisms. However, it was the first organic compound synthesized in a laboratory from inorganic materials (Wohler, 1828). This discovery was historically significant as it disproved the vitalism theory in chemistry.

Learn Urea Formula for Exam Success

Urea is one of chemistry’s most elegant and important compounds. With the formula CH4N2O (or CO(NH2)2), a molecular mass of 60 g/mol, and a nitrogen content of 46.67%, it connects topics across inorganic chemistry, organic chemistry, stoichiometry, agricultural science, and biochemistry.

Let us recap the most critical facts you must remember:

Fact	Value / Answer
Chemical Formula	CH4N2O or CO(NH2)2
Alternative Formula	H2N-CO-NH2
IUPAC Name	Carbonamide
Common Names	Urea, Carbamide
Molecular Mass	60.06 g/mol (use 60 in exams)
% Nitrogen	46.67%
% Carbon	20.00%
% Hydrogen	6.71%
% Oxygen	26.64%
Degree of Unsaturation	1 (the C=O bond)
Hybridization of C	sp2
Synthesis Reaction	CO2 + 2NH3 –> (NH2)2CO + H2O
Wohler Synthesis	NH4CNO –heat–> (NH2)2CO
Molar Mass for Mole Calculations	60 g/mol
Geometry	Trigonal planar

Whether you are preparing for your Class 10 board exams, tackling a Class 12 stoichiometry problem, or studying for NEET and JEE, a firm grasp of the urea formula and its applications will serve you well across multiple chapters and exam formats.

Related Important Formulas List

Category	Formula
Percentage	Percentage = (Part / Whole) × 100
Percentage Increase	((New − Original) / Original) × 100
Percentage Decrease	(Original − New) / Original) × 100
Average	Mean = (Sum of values) / n
Ratio	a : b = a / b
Proportion	a/b = c/d → ad = bc
Algebra Identity	(a + b)² = a² + 2ab + b²
Algebra Identity	(a − b)² = a² − 2ab + b²
Algebra Identity	a² − b² = (a + b)(a − b)
Cube Identity	(a + b)³ = a³ + 3a²b + 3ab² + b³
Cube Identity	(a − b)³ = a³ − 3a²b + 3ab² − b³
Quadratic Equation	ax² + bx + c = 0
Quadratic Formula	x = (-b ± √(b² − 4ac)) / 2a
Discriminant	Δ = b² − 4ac
AP nth term	aₙ = a + (n − 1)d
AP sum	Sₙ = n/2 [2a + (n−1)d]
Distance formula	d = √[(x₂ − x₁)² + (y₂ − y₁)²]
Midpoint	((x₁+x₂)/2 , (y₁+y₂)/2)
Trigonometry	sin θ = opposite / hypotenuse
Trigonometry	cos θ = adjacent / hypotenuse
Trigonometry	tan θ = opposite / adjacent
Identity	sin²θ + cos²θ = 1
Circle	Area = πr²
Circle	Circumference = 2πr
Rectangle	Area = length × width
Triangle	Area = ½ × base × height
Cube	Volume = a³
Cylinder	Volume = πr²h
Sphere	Volume = 4/3 πr³
Mean	x̄ = Σx / n
Probability	P(E) = favorable outcomes / total outcomes