CBSE Class 10 Chemistry Formulas Chapters wise
1. What Are Chemistry Formulas?
A chemistry formula is a symbolic representation of a chemical compound using element symbols and numerical subscripts. It tells you exactly which atoms are present and in what ratio.
Why it matters: Every reaction, every equation, every calculation in chemistry begins with knowing the correct formula. Without it, balancing equations or predicting products is impossible.
Three types of formulas you must know:
- Molecular Formula — shows actual number of atoms (e.g., H₂O)
- Empirical Formula — shows simplest whole-number ratio (e.g., CH₂O for glucose)
- Structural Formula — shows how atoms are bonded
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2. Basic Chemistry Formulas — Class 10
These are the foundational formulas every Class 10 student must memorize.
| Formula Name |
Formula |
Explanation |
Variables |
Example Use Case |
| Water |
H₂O |
Two hydrogen atoms, one oxygen |
H = Hydrogen, O = Oxygen |
Product of neutralization |
| Carbon Dioxide |
CO₂ |
One carbon, two oxygens |
C = Carbon, O = Oxygen |
Combustion reactions |
| Oxygen |
O₂ |
Diatomic oxygen molecule |
O = Oxygen |
Supports combustion |
| Hydrogen |
H₂ |
Diatomic hydrogen molecule |
H = Hydrogen |
Displacement reactions |
| Sodium Chloride (Table Salt) |
NaCl |
Ionic compound of Na⁺ and Cl⁻ |
Na = Sodium, Cl = Chlorine |
Salt formation reaction |
| Calcium Carbonate |
CaCO₃ |
Limestone compound |
Ca, C, O |
Thermal decomposition |
| Sodium Hydroxide |
NaOH |
Strong base |
Na, O, H |
Neutralization reactions |
| Hydrochloric Acid |
HCl |
Strong acid |
H, Cl |
Acid reactions |
| Sulfuric Acid |
H₂SO₄ |
Strong diprotic acid |
H, S, O |
Electrolysis, reactions |
| Ammonia |
NH₃ |
Alkaline gas |
N = Nitrogen, H |
Haber process |
| Magnesium Oxide |
MgO |
Basic oxide |
Mg, O |
Combustion of Mg |
| Iron (III) Oxide |
Fe₂O₃ |
Rust compound |
Fe, O |
Corrosion |
| Copper Sulfate |
CuSO₄ |
Blue crystalline salt |
Cu, S, O |
Displacement reactions |
| Calcium Oxide |
CaO |
Quicklime |
Ca, O |
Slaking of lime |
| Calcium Hydroxide |
Ca(OH)₂ |
Slaked lime |
Ca, O, H |
Testing CO₂ |
3. Water and Common Compound Formulas
Water — H₂O — is the most important molecule in chemistry. It is the universal solvent, a product of neutralization, and a reactant in hydrolysis.
Key water-related formulas:
| Reaction |
Formula/Equation |
| Formation of water |
2H₂ + O₂ → 2H₂O |
| Water dissociation |
H₂O ⇌ H⁺ + OH⁻ |
| Ionic product of water (Kw) |
Kw = [H⁺][OH⁻] = 1 × 10⁻¹⁴ at 25°C |
| pH of water |
pH = 7 (neutral) |
| Heavy water |
D₂O (deuterium oxide) |
Other common compound formulas:
| Compound |
Formula |
| Hydrogen Peroxide |
H₂O₂ |
| Nitric Acid |
HNO₃ |
| Phosphoric Acid |
H₃PO₄ |
| Acetic Acid |
CH₃COOH |
| Carbonic Acid |
H₂CO₃ |
| Potassium Hydroxide |
KOH |
| Sodium Carbonate (Washing Soda) |
Na₂CO₃ |
| Sodium Bicarbonate (Baking Soda) |
NaHCO₃ |
| Bleaching Powder |
Ca(OCl)Cl |
| Plaster of Paris |
CaSO₄·½H₂O |
4. Acid, Base, and Salt Formulas
Common Acids
| Acid Name |
Formula |
Type |
| Hydrochloric Acid |
HCl |
Strong |
| Sulfuric Acid |
H₂SO₄ |
Strong |
| Nitric Acid |
HNO₃ |
Strong |
| Acetic Acid |
CH₃COOH |
Weak |
| Carbonic Acid |
H₂CO₃ |
Weak |
| Phosphoric Acid |
H₃PO₄ |
Weak |
| Oxalic Acid |
H₂C₂O₄ |
Weak |
| Formic Acid |
HCOOH |
Weak |
Common Bases
| Base Name |
Formula |
Type |
| Sodium Hydroxide |
NaOH |
Strong |
| Potassium Hydroxide |
KOH |
Strong |
| Calcium Hydroxide |
Ca(OH)₂ |
Moderate |
| Ammonia |
NH₃ |
Weak |
| Magnesium Hydroxide |
Mg(OH)₂ |
Weak |
| Aluminum Hydroxide |
Al(OH)₃ |
Weak |
Salt Chemistry Formulas
Salts are formed when an acid reacts with a base. The general reaction is: Acid + Base → Salt + Water
| Salt Name |
Formula |
Formed From |
| Sodium Chloride |
NaCl |
HCl + NaOH |
| Potassium Nitrate |
KNO₃ |
HNO₃ + KOH |
| Calcium Sulfate |
CaSO₄ |
H₂SO₄ + Ca(OH)₂ |
| Ammonium Chloride |
NH₄Cl |
HCl + NH₃ |
| Ferrous Sulfate |
FeSO₄ |
H₂SO₄ + Fe |
| Copper Sulfate |
CuSO₄ |
H₂SO₄ + CuO |
| Sodium Acetate |
CH₃COONa |
CH₃COOH + NaOH |
| Zinc Sulfate |
ZnSO₄ |
H₂SO₄ + Zn |
5. Organic Chemistry Formulas — Class 11 & 12
Organic chemistry is built on carbon chains. Here is your essential reference.
Homologous Series Formulas
| Series |
General Formula |
Example |
| Alkanes |
CₙH₂ₙ₊₂ |
CH₄ (Methane), C₂H₆ (Ethane) |
| Alkenes |
CₙH₂ₙ |
C₂H₄ (Ethylene) |
| Alkynes |
CₙH₂ₙ₋₂ |
C₂H₂ (Acetylene) |
| Alcohols |
CₙH₂ₙ₊₁OH |
CH₃OH (Methanol) |
| Carboxylic Acids |
CₙH₂ₙ₊₁COOH |
CH₃COOH (Acetic Acid) |
| Aldehydes |
CₙH₂ₙO |
HCHO (Formaldehyde) |
| Ketones |
CₙH₂ₙO |
CH₃COCH₃ (Acetone) |
| Esters |
RCOOR’ |
CH₃COOC₂H₅ (Ethyl Acetate) |
Important Organic Compounds (Class 12)
| Compound |
Formula |
Key Reaction |
| Glucose |
C₆H₁₂O₆ |
Fermentation to ethanol |
| Sucrose |
C₁₂H₂₂O₁₁ |
Hydrolysis to glucose + fructose |
| Benzene |
C₆H₆ |
Electrophilic substitution |
| Toluene |
C₆H₅CH₃ |
Nitration |
| Aniline |
C₆H₅NH₂ |
Diazotization |
| Chloroform |
CHCl₃ |
Reimer-Tiemann reaction |
| Carbon Tetrachloride |
CCl₄ |
Solvent |
| Urea |
(NH₂)₂CO |
First organic compound synthesized |
6. Alcohol Formulas in Chemistry
Alcohols are organic compounds containing the —OH (hydroxyl) group.
| Alcohol Name |
Formula |
Class |
| Methanol (Wood Alcohol) |
CH₃OH |
Primary |
| Ethanol (Drinking Alcohol) |
C₂H₅OH |
Primary |
| Propan-1-ol |
C₃H₇OH |
Primary |
| Butan-1-ol |
C₄H₉OH |
Primary |
| Isopropanol |
(CH₃)₂CHOH |
Secondary |
| 2-Butanol |
CH₃CH(OH)C₂H₅ |
Secondary |
| 2-Methyl-2-propanol |
(CH₃)₃COH |
Tertiary |
| Ethylene Glycol |
C₂H₄(OH)₂ |
Diol |
| Glycerol |
C₃H₅(OH)₃ |
Triol |
| Phenol |
C₆H₅OH |
Aromatic alcohol |
Key reactions of alcohols:
- Dehydration: C₂H₅OH → C₂H₄ + H₂O (with H₂SO₄)
- Oxidation of ethanol: C₂H₅OH → CH₃COOH (via CH₃CHO)
- Fermentation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
7. Thermodynamics & Physical Chemistry Formulas
| Formula Name |
Formula |
Variables |
| Enthalpy Change |
ΔH = H_products − H_reactants |
H = enthalpy |
| Gibbs Free Energy |
ΔG = ΔH − TΔS |
T = temperature, S = entropy |
| Entropy Change |
ΔS = q_rev / T |
q = heat, T = temperature (K) |
| Ideal Gas Law |
PV = nRT |
P = pressure, V = volume, n = moles, R = 8.314, T = temp |
| Boyle’s Law |
P₁V₁ = P₂V₂ |
At constant temperature |
| Charles’s Law |
V₁/T₁ = V₂/T₂ |
At constant pressure |
| Avogadro’s Law |
V ∝ n |
At constant T and P |
| Mole Concept |
n = m/M |
m = mass, M = molar mass |
| Molarity |
M = n/V(L) |
n = moles, V = volume in liters |
| Molality |
m = n/kg(solvent) |
moles per kilogram |
8. Electrochemistry Formulas
| Formula Name |
Formula |
Explanation |
| Faraday’s First Law |
m = ZIt |
m = mass deposited, Z = electrochemical equivalent, I = current, t = time |
| Faraday’s Second Law |
m₁/m₂ = E₁/E₂ |
E = equivalent weight |
| Nernst Equation |
E = E° − (RT/nF)lnQ |
E° = standard EMF, Q = reaction quotient |
| Cell EMF |
E_cell = E_cathode − E_anode |
Standard reduction potentials |
| Relationship between ΔG and EMF |
ΔG = −nFE |
n = electrons, F = 96500 C/mol |
| Conductance |
G = 1/R |
R = resistance |
| Molar Conductivity |
Λm = κ/C |
κ = conductivity, C = concentration |
9. Chemical Equilibrium Formulas
| Formula Name |
Formula |
Explanation |
| Equilibrium Constant (Kc) |
Kc = [Products]/[Reactants] |
Concentration-based |
| Equilibrium Constant (Kp) |
Kp = Kc(RT)^Δn |
Pressure-based |
| Relationship Kp & Kc |
Kp = Kc(RT)^Δn |
Δn = change in moles of gas |
| pH Formula |
pH = −log[H⁺] |
[H⁺] = hydrogen ion concentration |
| pOH Formula |
pOH = −log[OH⁻] |
| pH + pOH |
pH + pOH = 14 |
At 25°C |
| Ka (Acid dissociation) |
Ka = [H⁺][A⁻]/[HA] |
Strength of weak acid |
| Kb (Base dissociation) |
Kb = [BH⁺][OH⁻]/[B] |
Strength of weak base |
| Henderson-Hasselbalch |
pH = pKa + log([A⁻]/[HA]) |
Buffer solution equation |
10. Solved Examples
Example 1: Finding pH of HCl solution Given: 0.01 M HCl solution. Find pH.
HCl is a strong acid → completely dissociates. [H⁺] = 0.01 = 10⁻² pH = −log(10⁻²) = 2
Example 2: Neutralization Reaction HCl + NaOH → NaCl + H₂O
This is a classic acid-base neutralization. The product is sodium chloride (table salt) and water. The reaction is exothermic.
Example 3: Moles Calculation Find moles in 36 g of water (H₂O). Molar mass of H₂O = 18 g/mol. n = m/M = 36/18 = 2 moles
Example 4: Fermentation of Glucose C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
Glucose breaks down into ethanol and carbon dioxide in the presence of yeast. This is used in the brewing and bread industry.
11. Common Mistakes Students Make
Students often write H₂O₂ instead of H₂O for water in a hurry. Always recheck subscripts.
Confusing molarity (moles per liter) with molality (moles per kilogram) is extremely common in Class 12 numerical problems.
Writing NaCO₃ instead of Na₂CO₃ for sodium carbonate — sodium has a +1 charge, carbonate has −2, so you need two sodiums.
Forgetting to balance equations before applying stoichiometry causes incorrect mole calculations.
Misidentifying primary, secondary, and tertiary alcohols during Class 12 organic reactions leads to wrong product prediction.
12. Memory Tips & Tricks
For strong acids, remember: Happy Clown Never Sells Poison Beer → HCl, HNO₃, H₂SO₄, HClO₄, HBr, HI
For alkane formula CₙH₂ₙ₊₂: think “methane = 1 carbon, 4 hydrogens = 2(1)+2 = 4. It checks out every time.”
For pH scale: below 7 = acidic, exactly 7 = neutral, above 7 = basic. Think: “7 is the peacekeeping middle.”
For Kw = 10⁻¹⁴: “14 is neutral — same as the pH+pOH always adding to 14.”
For alcohol naming: the suffix -ol always tells you there’s an OH group. Meth-an-ol, Eth-an-ol — count the carbons in the prefix.
Conclusion
Chemistry formulas are not random strings of letters and numbers — they are precise, logical representations of the world around you. From the water you drink (H₂O) to the salt on your food (NaCl), from the acid in your stomach (HCl) to the fuel in combustion engines (C₈H₁₈), chemistry formulas describe reality at its most fundamental level.
For Class 10 students, mastering basic compound formulas and salt reactions builds the foundation. For Class 11 and 12 students, organic chemistry formulas, thermodynamic equations, and electrochemical expressions become the tools that unlock higher scores and deeper understanding.
The key is consistency review your formula chart daily, practice solved examples, and never skip balancing equations. Every formula you memorize today is a mark secured in tomorrow’s exam.
Chemistry Formula Class 10 related FAQs
Q1. What is the formula of water in chemistry?
The formula of water is H₂O — two hydrogen atoms bonded to one oxygen atom. It is a covalent compound with a bent molecular shape and a bond angle of approximately 104.5°. Water is the most abundant compound on Earth and acts as the universal solvent.
Q2. What are the basic chemistry formulas for Class 10?
Key Class 10 formulas include H₂O (water), CO₂ (carbon dioxide), NaCl (salt), HCl (hydrochloric acid), NaOH (sodium hydroxide), CaCO₃ (calcium carbonate), and H₂SO₄ (sulfuric acid). These cover acids, bases, salts, and oxide compounds essential for board exams.
Q3. What is the formula for common salt in chemistry?
Common salt is sodium chloride, with the formula NaCl. It is an ionic compound formed by the neutralization of hydrochloric acid (HCl) with sodium hydroxide (NaOH). The reaction is: HCl + NaOH → NaCl + H₂O.
Q4. What is the alcohol formula in chemistry?
The general formula for alcohols is CₙH₂ₙ₊₁OH. The most common alcohols are methanol (CH₃OH) and ethanol (C₂H₅OH). Alcohols contain a hydroxyl (—OH) group attached to a saturated carbon atom and are classified as primary, secondary, or tertiary.
Q5. What are the most important chemistry formulas for Class 12?
For Class 12, the most important formulas include the Nernst equation, Henderson-Hasselbalch equation, Gibbs free energy (ΔG = ΔH − TΔS), Faraday’s laws, Kp and Kc relationships, and organic chemistry reactions like esterification, aldol condensation, and Cannizzaro reaction.
Q6. What is the formula for baking soda and washing soda?
Baking soda is sodium bicarbonate: NaHCO₃. Washing soda is sodium carbonate: Na₂CO₃·10H₂O. Both are sodium-based salts but serve different purposes — baking soda is used in cooking and antacids, while washing soda is used as a cleaning agent.
Q7. How do I remember chemistry formulas easily?
Use mnemonics, write formulas repeatedly, and practice balancing equations daily. Group similar compounds together (all acids starting with H, all hydroxides ending with OH). Creating a formula chart and sticking it near your study desk is one of the most effective techniques students use.
Q8. What is the difference between molecular formula and empirical formula?
A molecular formula shows the actual number of atoms in a compound (e.g., C₆H₁₂O₆ for glucose). An empirical formula shows the simplest ratio (CH₂O for glucose). The molecular formula is always a whole-number multiple of the empirical formula and is used in actual chemical equations.
