Class 11 Chemistry - Chapter 1: Basic Concepts of Chemistry
Importance of Chemistry
- Chemistry is fundamental to understanding various substances and their interactions.
- Discusses how chemical combinations and laws affect our daily lives.
Key Concepts Introduced
- Significant Figures: Importance in measurements and calculations.
- Elements: Basic substances that cannot be broken down.
- Mixtures: Combinations of two or more substances.
- Chemical Combination: How elements combine to form compounds.
- Laws of Chemical Combination: Five major laws governing chemical reactions.
Laws of Chemical Combination
- Law of Conservation of Mass:
- Discovered in the 1740s-1780s.
- States that in a chemical reaction, mass is neither created nor destroyed.
- The mass of the reactants equals the mass of the products.
- Example:
- Carbon + Oxygen → Carbon Dioxide
- Atomic mass of Carbon = 12, Oxygen = 16.
- Calculation: 1 C (12) + 2 O (16x2 = 32) = 44 (Reactants) = 44 (Products).
Practice Problem
- Question:
- 1.5 grams of ethane combusting produces 44 grams of carbon dioxide and 2.7 grams of water.
- Show that the reaction obeys the law of conservation of mass.
Steps to Solve:
- Write the balanced reaction for the combustion of ethane.
Note: Further calculations and details can be added as per the reaction to prove the law of conservation of mass.