balancing chemical reactions

• A chemical reaction is a process in which the properties of the original substance change into new substances with different physical and chemical properties
• Examples of chemical reactions


  • Fireworks
  • Nail or any metal
• Physical reaction/change


  Melting of ice into water, freezing of water into ice, crumpling of paper
• Distinguishing factor between chemical and physical reactions

  In a chemical reaction, there is a change in the compounds, not just the elements
• Evidences of a chemical reaction

  • Change of color
  • Formation of gas
  • Temperature change
  • Change in smell
  • Formation of precipitate
• Reactant


  Substance or group of substances that enter a chemical reaction
• Product


  Substance or group of substances that are produced in a chemical reaction
• The law of conservation of mass states that matter is neither created nor destroyed in any chemical reaction. The total mass of the reactants must be equal to the total mass of the products.
• Steps to identify reactants and products in a chemical equation

  1. Identify the reactants

  2. Identify the products
• Examples of chemical equations

  • Photosynthesis: Carbon dioxide + Water → Glucose + Oxygen gas
• Coefficient


  The whole number in front of a chemical formula
• Subscript


  The small number written below an element in a chemical formula
• Steps to balance a chemical equation

  1. Identify the reactants and products

  2. Add coefficients to balance the equation
• The equation is balanced when the number of atoms of each element is the same on both sides of the equation.