Some Basic Concepts of Chemistry

This is the foundation of quantitative chemistry. Do not rush this. If you master the Mole Concept here, the rest of Physical Chemistry (Solutions, Kinetics, Equilibrium) becomes easy.

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⚠️ Prerequisites

Basic Algebra (Linear equations & ratios)
Scientific Notation ($10^x$) & Significant Figures
Unit Conversions (Liters $\leftrightarrow$ $cm^3$, kg $\leftrightarrow$ g)

🧠 Study Approach

Quantitative & Mathematical. Treat this like a math chapter. Write down variables ($n$, $V$, $M$), identify the formula, and check your units.

Study Sequence

1. Nature of Matter

Elements, Compounds, Mixtures. Learn the difference between Homogeneous and Heterogeneous mixtures.

2. Laws of Chemical Combination

Conservation of Mass, Definite Proportions, Multiple Proportions, Gaseous Volumes (Gay Lussac), and Avogadro's Law.

3. Atomic & Molecular Mass

Average Atomic Mass (Isotopes). Formula Mass vs Molecular Mass.

4. The Mole Concept (CRITICAL)

Visualize this: 1 Mole = Mass (Molar Mass) = Volume (22.7L at STP) = Number ($6.022 \times 10^{23}$).

5. Percentage Composition

Calculating Empirical Formula and Molecular Formula from mass percentages.

6. Stoichiometry & Percentage Yield

Balancing equations. Finding Limiting Reagent. Calculating Percentage Yield (Actual/Theoretical × 100).

7. Reactions in Solutions

Mass %, Mole Fraction, Molarity (M), and Molality (m). Dilution Equation ($M_1V_1 = M_2V_2$).

8. Advanced Concentration Terms

• Volume Strength of $H_2O_2$: Relates to Molarity/Normality. ($Vol. Strength = 11.2 \times M$). • Labeling of Oleum: Percentage labeling of fuming sulphuric acid ($H_2S_2O_7$). • Hardness of Water: Measured in ppm (parts per million) in terms of $CaCO_3$ equivalents.

🎯 How to Practice

Start with Unit Conversions. If you can't convert mL to L easily, you will fail Molarity questions.

Solve 20+ basic Mole Conversions (Mass $\leftrightarrow$ Mole $\leftrightarrow$ Particles). Do this until it's intuitive.

For Limiting Reagent, always calculate moles of reactants first, then divide by their stoichiometric coefficient. The lowest value indicates the limiting reagent.

📝 Quick Revision Notes

$$n = \frac{Mass}{Molar Mass} = \frac{Particles}{N_A} = \frac{Vol(STP)}{22.7}$$ $$\text{Percentage Yield} = \frac{\text{Actual}}{\text{Theoretical}} \times 100$$ $$M = \frac{n_{solute}}{V_{sol}(L)}$$ $$\text{Vol Strength } H_2O_2 = 11.2 \times M$$ $$ppm = \frac{\text{Mass Solute}}{\text{Mass Solution}} \times 10^6$$

*Molarity changes with Temperature, Molality does not.

Lesson Plan: Basic Concepts of Chemistry