Types of Chemical Reactions

Types of Reactions

• Synthesis Reactions: Two or more substances combine to form a new compound.
  • Example: 2H2 + O2 → 2H2O
• Decomposition Reactions: A single substance breaks down into two or more substances.
  • Example: 2H2O → 2H2 + O2
• Replacement Reactions: One element replaces another element in a compound.
  • Example: Zn + CuSO4 → ZnSO4 + Cu
• Combustion Reactions: A substance reacts with oxygen to produce heat and light.
  • Example: 2CH4 + 3O2 → 2CO2 + 3H2O
• Neutralization Reactions: An acid reacts with a base to form a salt and water.
  • Example: HCl + NaOH → NaCl + H2O
• Oxidation-Reduction Reactions: One substance loses electrons (oxidized) while another substance gains electrons (reduced).
  • Example: 2Na + Cl2 → 2NaCl

Balancing Equations

• Step 1: Write the unbalanced equation: Write the reactants on the left and products on the right.
• Step 2: Count the atoms: Count the number of atoms of each element on both the reactant and product sides.
• Step 3: Balance the atoms: Add coefficients (numbers in front of formulas) to balance the number of atoms of each element.
  • Start with the elements that appear in the greatest number of formulas
  • Balance elements that appear in multiple formulas last
• Step 4: Check the equation: Verify that the number of atoms of each element is equal on both sides.
• Tips:
  • Balance elements that are combined in a formula unit (e.g. water, H2O) together
  • Don't change the subscripts (numbers in the formula) when balancing an equation

Types of Reactions

• Synthesis reactions involve the combination of two or more substances to form a new compound, such as 2H2 + O2 → 2H2O.
• Decomposition reactions involve a single substance breaking down into two or more substances, such as 2H2O → 2H2 + O2.
• Replacement reactions involve one element replacing another element in a compound, such as Zn + CuSO4 → ZnSO4 + Cu.
• Combustion reactions involve a substance reacting with oxygen to produce heat and light, such as 2CH4 + 3O2 → 2CO2 + 3H2O.
• Neutralization reactions involve an acid reacting with a base to form a salt and water, such as HCl + NaOH → NaCl + H2O.
• Oxidation-reduction reactions involve one substance losing electrons (oxidized) while another substance gains electrons (reduced), such as 2Na + Cl2 → 2NaCl.

Balancing Equations

• The first step in balancing an equation is to write the unbalanced equation, separating reactants from products.
• The second step is to count the atoms of each element on both the reactant and product sides.
• The third step is to balance the atoms by adding coefficients (numbers in front of formulas) to ensure equal numbers of atoms of each element on both sides.
• Start balancing with elements that appear in the greatest number of formulas, and balance elements that appear in multiple formulas last.
• The fourth step is to check the equation to verify that the number of atoms of each element is equal on both sides.
• Tips for balancing equations include balancing elements that are combined in a formula unit (e.g., water, H2O) together, and not changing the subscripts (numbers in the formula) when balancing an equation.

Learn about the different types of chemical reactions, including synthesis, decomposition, replacement, and combustion reactions. Understand the examples and characteristics of each reaction type.