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,

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

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

Determination of Water Hardness by EDTA Method

EDTA is the abbreviation for Ethylene Diamine Tetra Acetic acid.

Pure EDTA dissolves in water with great difficulty and in very small quantities. Conversely, its di-sodium salt dissolves quickly and completely. Hence, for common experimental purposes, the di-sodium derivative of EDTA is used.

EDTA is a hexadentate ligand. It binds metal ions present in water, such as $Ca^{+2}$ or $Mg^{+2}$, to form a highly stable chelate complex. These metal ions are bonded via oxygen or nitrogen atoms from the EDTA molecule. Therefore, this method is called complexometric titration.

Principle of the EDTA Method

The di-sodium salt of EDTA forms complexes with $Ca^{+2}$ and $Mg^{+2}$ as well as with many other metal... Continue reading "Determining Water Hardness: The EDTA Titration Method" »

1. Sources of Water

2. Impurities in Water

3. Hardness of Water

Definition

Hardness... Continue reading "Water Chemistry: Hardness, Alkalinity, and Treatment" »