Chemistry Basics – SBI PO General Awareness & Current Affairs
(For the “Chemistry Basics” section of the SBI PO exam)
1. Simple Explanation
Chemistry is the science that studies matter: its composition, structure, properties, changes, and the energy involved in those changes. In the SBI PO syllabus, you will need a solid grounding in the fundamentals – from atoms and molecules to acids, bases, and industrial processes – because many current‑affairs questions revolve around chemistry‑related topics such as the Haber process, ozone depletion, plastic pollution, and green chemistry.
2. Key Points
| Category | What to Know | Why It Matters for SBI PO |
|---|---|---|
| Atomic Structure | - Protons, neutrons, electrons - Atomic number (Z) = # protons - Mass number (A) = Z + neutrons - Isotopes: same Z, different A - Charge: + for protons, – for electrons |
Many questions ask you to identify elements, understand isotopes in nuclear medicine, and calculate atomic masses. |
| Periodic Table | - 7 periods, 18 groups - Metals (s, p, d, f blocks) - Nonmetals & Metalloids - Trends: electronegativity ↑, ionization energy ↑, atomic radius ↓ across a period; ↓, ↑ down a group. |
Helps in identifying industrially important elements (Fe, Cu, Al, Zn) and their typical uses. |
| Chemical Bonding | - Ionic (transfer of electrons, e.g., NaCl) - Covalent (sharing; single, double, triple bonds) - Metallic (electron sea) - Hydrogen bonds (weak, important in DNA, water). |
Determines physical properties of compounds; used in explaining why certain materials are good conductors, insulators, or why water is unique. |
| Stoichiometry & Balancing | - Mole concept (Avogadro’s number 6.02×10²³) - Molar mass (g/mol) - Mole–mass–mass relationships - Balancing equations (atom & charge conservation). |
Core to solving quantitative questions about production of fertilizers, fuels, and chemical safety. |
| Acids & Bases | - Definitions: Arrhenius, Brønsted–Lowry, Lewis. - pH = –log[H⁺]; pOH = –log[OH⁻]; pH + pOH = 14. - Neutralization: acid + base → salt + water. - Indicators: phenolphthalein, methyl orange. |
Frequently asked in environmental questions (acid rain, wastewater treatment) and in industrial processes (hydrogenation, bleaching). |
| Redox Reactions | - Oxidation state changes. - Half‑reaction method (oxidation + reduction). - Electrochemical cells: galvanic (spontaneous) and electrolytic (non‑spontaneous). |
Key to questions on batteries, corrosion, industrial metal extraction (e.g., aluminium from alumina). |
| Key Industrial Processes | - Haber–Bosch (NH₃ synthesis) – fertilizers. - Ostwald (NO₂ → NO → N₂O₄) – nitric acid. - Koch (CO + H₂O → C + 2H₂) – hydrogen production. - Electrolysis of NaCl (chlorine, NaOH, H₂). |
Underlie many current‑affairs topics: fertilizer prices, energy crisis, environmental pollution. |
| Environmental & Green Chemistry | - Ozone layer: UV absorption, CFCs. - Acid rain: SO₂, NOₓ → H₂SO₄, HNO₃. - Plastic pollution: PET, PP, PE. - Green chemistry principles: waste prevention, energy efficiency. |
Directly tied to policy and regulatory questions on environmental protection, sustainability, and corporate responsibility. |
3. Worked Example
Problem:
How many grams of water (H₂O) are produced when 10 g of pure hydrogen gas (H₂) reacts completely with excess oxygen (O₂) according to the reaction:
[ 2,\text{H}_2 + \text{O}_2 \rightarrow 2,\text{H}_2\text{O} ]
Solution Steps
-
Write the balanced equation.
Already balanced above. -
Convert the given mass of H₂ to moles.
[ \text{Molar mass of H}_