Essential Chemistry Formulas and Reference

Miscellaneous Formulas

• Area of a Circle: 3.14r²
• Volume: Area × Height
• Density: Mass / Volume
• % Composition of Element: [(# of atoms of element) × (atomic weight of element)] / formula weight of substance × 100
• Molarity: (moles of solute) / (volume of solution in Liters)
• Bond Order: (# shared electrons) - (# nonbonding electrons) / 2
• Pressure: Force / Area
• Pressure × Volume: nRT
• Density of Gas: (Pressure × Molar Mass) / (R × Temperature)
• Molarity of Gas: (Density × R × Temperature) / Pressure

Temperature and Chemical Conversions

• Celsius to Kelvin: K = C + 273.15
• Kelvin to Celsius: C = K - 273.15
• Celsius to Fahrenheit: F = 9/5(C) + 32
• Fahrenheit to Celsius: C = 5/9(F - 32)
• 1 amu: 1.66054 × 10⁻²⁴ g
• Grams

🥪 Chemistry and Physics Fundamentals

Key Formulas

Density Triangle:

• Density (D) = Mass (m) ÷ Volume (V)

• Mass (m) = Density (D) × Volume (V)

• Volume (V) = Mass (m) ÷ Density (D)

Other Core Formulas & Rules:

• Neutrons = Mass Number − Atomic Number

• Valence Electrons = Outermost shell electrons

• Charge = Protons − Electrons (for ions)

• Stable Octet = 8 valence electrons (or 2 for small atoms like Helium)

Chemical Bonding

• Ionic Bond = Metal + Non-metal (electrons are transferred)

• Covalent Bond = Non-metal + Non-metal (electrons are shared)

• Diatomic molecules: H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂

Power Formula:                   Energy Formula:
P = V × I                                E = P × t  

Concepts

• Conductors let

Catalytic Reforming Process Fundamentals

• Converts low-octane naphtha into high-octane reformate, which is used for gasoline blending and aromatics production.
• Feed is mixed with hydrogen, heated, and passed over a catalyst in fixed-bed reactors.
• Major reactions include dehydrogenation to aromatics, isomerization to branched paraffins, and mild hydrocracking.
• Operating conditions are typically 450–520 °C temperature and 10–45 atm pressure.
• The catalyst used is platinum on alumina or bimetallic Pt–Re on alumina.
• Main products are reformate, hydrogen, LPG, and light hydrocarbons.

Fluid Catalytic Cracking (FCC) Technology

1. FCC converts heavy gas oils into valuable products like high-octane gasoline, LPG, and olefins.
2. Preheated feed contacts hot,

Acid-Base Equilibrium Practice Problems

1. The conjugate acid of HAsO₄²⁻ is:
   Answer: C. H₂AsO₄⁻
2. Which of the following tests could be used to distinguish between 1.0 M HCl and 1.0 M NaOH?
   Answer: C. II and III only
3. Consider the following Brønsted-Lowry equilibrium:
   C₆H₅NH₂(aq) + H₂O(l) ⇌ C₆H₅NH₃⁺(aq) + OH⁻(aq)
   The substances acting as acids and bases from left to right are:
   Answer: C. Base, acid, acid, base
4. Which of the following are amphiprotic?
   I. H₂O, II. NH₄⁺, III. HCO₃⁻
   Answer: B. I and III only
5. Which of the following represents the equilibrium expression for the ionization of water?
   Answer: A.
6. Which of the following will have the lowest electrical conductivity?
   Answer: D. 1.00 M H₃PO₄
7. Water acts as an acid when

Hybridization in Hydrocarbons

Ethane (C₂H₆)

Ethane is sp³ hybridized with a tetrahedral geometry and a bond angle of 109.5°. One sp³ orbital of each carbon atom undergoes internuclear axial overlapping to form a sigma (σ) bond. Three sp³ orbitals of each carbon atom undergo internuclear axial overlapping with the 1s orbital of hydrogen atoms to form three sigma bonds each.

Ethene (C₂H₄)

In C₂H₄, each carbon atom is sp² hybridized and lies in a trigonal planar geometry with a bond angle of 120°. Out of three sp² hybrid orbitals:

• One sp² orbital of one carbon atom undergoes internuclear axial overlapping with the sp² orbital of another carbon atom to form one sigma (σ) bond.
• Two sp² orbitals of each carbon atom undergo internuclear

Dynamic Equilibrium and System Properties

1. Dynamic Equilibrium (⇄): This is a dynamic, not static, state. Temperature relates to the speed of molecules. Concentration formulas include C = n/v, n = C * v, and v = n/C.

• Rate: The rate of the forward reaction equals the rate of the reverse reaction.
• Concentration: Concentrations remain constant at equilibrium, though they are not necessarily equal.
• Molecules: Molecules are destroyed and created at the same speed.
• System Type: Must be a closed system where no matter flows in or out. It requires constant temperature (no phase change, color change, or pressure change).

Inert Gases and Catalysts

• Inert Gases: Adding an inert gas (e.g., Ar, He) results in no shift in equilibrium.
• Catalysts: Adding a catalyst

Fundamentals of Analytical Chemistry Techniques

Analytical techniques are methods used to identify, quantify, and understand the chemical composition and structure of substances. These techniques are broadly classified into qualitative (what is present) and quantitative (how much is present) methods.

Major Analytical Methods

Common analytical techniques include:

• Gravimetric Analysis: Involves measuring the mass of a substance to determine the amount of analyte.
• Titrimetric (Volumetric) Analysis: Based on measuring the volume of a standard solution required to react with the analyte.
• Spectroscopic Methods: Measure the interaction between light and matter.
• Electrochemical Methods: Based on the measurement of electrical properties.

Preparation and Standardization

EDTA Titration and Water Hardness Calculation

EDTA Structure

EDTA (C₁₀H₁₆N₂O₈) is a hexadentate ligand that binds metal ions through four carboxyl (–COOH) groups and two amine (–NH₂) groups.

Titration Procedure (Water Hardness Test)

1. Take a 50 mL water sample.
2. Add buffer (pH 10) and Eriochrome Black T indicator (resulting in a wine-red color).
3. Titrate with EDTA until the color changes to sky blue (the end point).
4. Note the volume of EDTA used (V).

Reaction

M²⁺ + EDTA⁴⁻ → [M-EDTA]²⁻

Calculation Formula

Hardness (ppm) = (V × M × 1,000,000) / Vₛₐₘₗₔₗₑ

• M = EDTA molarity
• V = Volume of EDTA used (mL)
• Vₛₐₘₗₔₗₑ = Sample volume (mL)

Water Impurities and Boiler Problems

Hardness

The presence of calcium (Ca²⁺)

🔹 Isomerism (Class 11)

Definition:

Isomers are compounds having the same molecular formula but a different arrangement of atoms or different spatial arrangement, resulting in different properties.

1️⃣ Structural Isomerism

(Atoms have a different connection)

(A) Chain Isomerism

Definition:

Same molecular formula but a different carbon chain (straight or branched).

Example:

• C₄H₁₀
  • n-Butane → CH₃–CH₂–CH₂–CH₃
  • Isobutane → CH₃–CH(CH₃)–CH₃
• C₅H₁₂
  • Pentane
  • Isopentane
  • Neopentane

(B) Position Isomerism

Definition:

Same carbon chain and functional group, but the position of the functional group or multiple bond is different.

Example:

• C₃H₈O
  • 1-Propanol (–OH on C-1)
  • 2-Propanol (–OH on C-2)
• C₄H₈
  • 1-Butene
  • 2-Butene

(C) Functional

## Amino Acids and Peptides
### 1. \alpha-Amino Acids: Structure and Classification
Amino acids are the fundamental building blocks of proteins. An **\alpha-amino acid** consists of a central \alpha-carbon atom bonded to four distinct groups: an amino group (-\text{NH}_2), a carboxylic acid group (-\text{COOH}), a hydrogen atom (-\text{H}), and a variable side chain (-\text{R}).
#### Classification based on R-group polarity:
 * **Non-polar / Hydrophobic:** Side chains are aliphatic hydrocarbons or aromatic rings (e.G., Alanine, Valine, Phenylalanine).
 * **Polar / Uncharged:** Side chains contain hydrophilic groups like hydroxyls or amides (e.G., Serine, Glutamine).
 * **Acidic / Negatively Charged:** Side chains contain an extra carboxyl group... Continue reading "Bioelements and their importance" »