Chapter 1: Chemical Reactions and Equations ATOM BOMB
Chapter 1: Chemical Reactions and Equations
What is a Chemical Reaction?
A chemical reaction is a process where reactants transform into products, accompanied by energy changes. These changes can be observed as:
Change in color: (e.g., burning of magnesium ribbon).
Formation of a precipitate: (e.g., mixing of solutions of barium chloride and sodium sulfate).
Evolution of gas: (e.g., reaction between acids and metals).
Change in temperature: (e.g., combustion of fuels).
Types of Chemical Reactions
Combination Reaction: Two or more substances combine to form a single product.
Example:
2H2+O2→2H2O2H2+O2→2H2O (Hydrogen combines with oxygen to form water).
Decomposition Reaction: A single reactant breaks down into two or more products.
Example:
2KClO3→2KCl+3O22KClO3→2KCl+3O2 (Potassium chlorate decomposes into potassium chloride and oxygen).
Displacement Reaction: A more reactive element displaces a less reactive one from its compound.
Example:
Zn+CuSO4→ZnSO4+CuZn+CuSO4→ZnSO4+Cu (Zinc displaces copper from copper sulfate).
Double Displacement Reaction: The ions of two compounds exchange to form new compounds.
Example:
NaCl+AgNO3→NaNO3+AgClNaCl+AgNO3→NaNO3+AgCl (Formation of silver chloride from sodium chloride and silver nitrate).
Redox Reactions: Simultaneous oxidation and reduction processes. Example: 2Na+Cl2→2NaCl2Na+Cl2→2NaCl (Sodium is oxidized, chlorine is reduced).
Balancing Chemical Equations
Law of Conservation of Mass: Matter is neither created nor destroyed in a chemical reaction. The mass of reactants equals the mass of products.
Steps to Balance Equations:
Count the number of atoms of each element on both sides.
Add coefficients to balance the number of atoms.
Energy in Reactions
Exothermic Reactions: Release energy (usually heat). Example: C+O2→CO2C+O2→CO2
Endothermic Reactions: Absorb energy (usually heat). Example: Photosynthesis in plants:
6CO2+6H2O+light energy→C6H12O6+6O26CO2+6H2O+light energy→C6H12O6+6O2.
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