Types of Chemical Reactions

Study Notes

Synthesis Reaction: A reaction where two or more substances combine to form a new compound.
- Example: 2H2 + O2 → 2H2O
Decomposition Reaction: A reaction where a single compound breaks down into two or more substances.
- Example: 2H2O → 2H2 + O2
Replacement Reaction: A reaction where one element replaces another element in a compound.
- Example: Zn + CuSO4 → ZnSO4 + Cu
Combustion Reaction: A reaction where a substance reacts with oxygen to produce heat and light.
- Example: 2CH4 + 3O2 → 2CO2 + 3H2O

Reactants: The substances that are present at the start of a reaction.
Products: The substances that are formed as a result of a reaction.
Coefficients: Numbers that are placed in front of formulas of reactants or products to indicate the mole ratio of the substances in the reaction.
Balancing Equations: The process of adding coefficients to ensure that the number of atoms of each element is the same on both the reactant and product sides.

Write the unbalanced equation: Write the reactants and products with their respective formulas.
Count the atoms: Count the number of atoms of each element on both the reactant and product sides.
Add coefficients: Add coefficients to balance the equation by ensuring that the number of atoms of each element is the same on both sides.
Check the equation: Check the equation to ensure that it is balanced and that the coefficients are in the lowest possible ratio.

Predicting the outcome of a reaction: Chemical equations allow us to predict the products and reactants of a reaction.
Determining the quantity of reactants and products: Chemical equations allow us to calculate the amount of reactants required and the amount of products formed.
Understanding chemical reactions: Chemical equations help us understand the mechanism of chemical reactions and the interactions between molecules.

A Synthesis Reaction combines two or more substances to form a new compound, e.g., 2H2 + O2 → 2H2O.
A Decomposition Reaction breaks down a single compound into two or more substances, e.g., 2H2O → 2H2 + O2.
A Replacement Reaction replaces one element with another in a compound, e.g., Zn + CuSO4 → ZnSO4 + Cu.
A Combustion Reaction reacts a substance with oxygen to produce heat and light, e.g., 2CH4 + 3O2 → 2CO2 + 3H2O.

Reactants are the substances present at the start of a reaction.
Products are the substances formed as a result of a reaction.
Coefficients are numbers that indicate the mole ratio of substances in a reaction.

Step 1: Write the unbalanced equation, including reactants and products with their formulas.
Step 2: Count the atoms, counting the number of atoms of each element on both the reactant and product sides.
Step 3: Add coefficients, balancing the equation by ensuring the number of atoms of each element is the same on both sides.
Step 4: Check the equation, verifying that the equation is balanced and the coefficients are in the lowest possible ratio.

Predicting the outcome of a reaction, allowing us to anticipate products and reactants.
Determining the quantity of reactants and products, enabling calculations of required reactants and formed products.
Understanding chemical reactions, helping us comprehend the mechanism of chemical reactions and molecular interactions.