Balancing Chemical Equations

Balancing Equations

• Why balance equations?: To ensure the law of conservation of mass is followed, which states that matter cannot be created or destroyed in a chemical reaction.
• Steps to balance an equation:
  1. Write the unbalanced equation with reactants on the left and products on the right.
  2. Count the number of atoms of each element on both sides.
  3. Identify the elements that are not balanced.
  4. Add coefficients (numbers in front of formulas) to balance the equation.
  5. Check the equation to ensure it is balanced.
• Tips for balancing equations:
  • Start with elements that appear in only one compound on each side.
  • Balance elements that are combined in a single compound (e.g., oxygen in water).
  • Balance elements that are in their elemental forms (e.g., oxygen gas).
  • Use fractions as coefficients as a last resort.

Acid-Base Reactions

• Definitions:
  • Acid: A substance that donates a proton (H+ ion).
  • Base: A substance that accepts a proton (H+ ion).
  • Neutralization: The reaction between an acid and a base to form a salt and water.
• Types of acid-base reactions:
  • Arrhenius: Involves the transfer of H+ ions from an acid to a base.
  • Bronsted-Lowry: Involves the transfer of a proton from an acid to a base.
  • Lewis: Involves the transfer of an electron pair from a base to an acid.
• Characteristics of acid-base reactions:
  • They are often exothermic (release heat).
  • They can be neutralization reactions or acid-base catalysis.
  • They can be reversible or irreversible.
• Examples of acid-base reactions:
  • HCl (acid) + NaOH (base) → NaCl (salt) + H2O (water)
  • CH3COOH (acid) + NaHCO3 (base) → CH3COONa (salt) + H2O (water)

Balancing Equations

• The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction.
• Balancing equations ensures that the law of conservation of mass is followed.
• The steps to balance an equation are:
• Writing the unbalanced equation with reactants on the left and products on the right.
• Counting the number of atoms of each element on both sides.
• Identifying the elements that are not balanced.
• Adding coefficients to balance the equation.
• Checking the equation to ensure it is balanced.
• Tips for balancing equations include:
• Starting with elements that appear in only one compound on each side.
• Balancing elements that are combined in a single compound.
• Balancing elements that are in their elemental forms.
• Using fractions as coefficients as a last resort.

Acid-Base Reactions

• An acid is a substance that donates a proton (H+ ion).
• A base is a substance that accepts a proton (H+ ion).
• Neutralization is the reaction between an acid and a base to form a salt and water.
• There are three types of acid-base reactions:
• Arrhenius reactions involve the transfer of H+ ions from an acid to a base.
• Bronsted-Lowry reactions involve the transfer of a proton from an acid to a base.
• Lewis reactions involve the transfer of an electron pair from a base to an acid.
• Acid-base reactions are often exothermic (release heat).
• They can be neutralization reactions or acid-base catalysis.
• They can be reversible or irreversible.
• Examples of acid-base reactions include:
• HCl (acid) + NaOH (base) → NaCl (salt) + H2O (water)
• CH3COOH (acid) + NaHCO3 (base) → CH3COONa (salt) + H2O (water)