Balancing equations

• What is the purpose of chemical equations in a chemical reaction?

  To show what is happening in a chemical reaction
• What is an example of a word equation for a chemical reaction?

  Methane burns in oxygen to produce carbon dioxide and water
• What are the reactants in the example of methane burning?

  Methane and oxygen
• What are the products in the example of methane burning?

  Carbon dioxide and water
• What symbol is used to indicate that reactants react to form products in a chemical equation?

  A single arrow
• What is the difference between word equations and symbol equations?

  Symbol equations use chemical symbols instead of words
• What is the chemical symbol for methane?

  $CH_4$
• What is the chemical symbol for oxygen?


  $O_2$
• Why do we write $O_2$ instead of $O$ in chemical equations?


  Because oxygen exists as a molecule made up of two atoms
• What is the first step in balancing a chemical equation?

  Ensure the same total number of each type of atom on both sides of the arrow
• How many carbon, hydrogen, and oxygen atoms are on the left side of the methane combustion equation?

  1 carbon, 4 hydrogens, and 2 oxygens
• How many carbon, hydrogen, and oxygen atoms are on the right side of the methane combustion equation?

  1 carbon, 2 hydrogens, and 3 oxygens
• What is the first rule of balancing chemical equations?

  You cannot change any of the small numbers in the chemical formulas
• What do the big numbers in front of elements or compounds represent in a chemical equation?

  They represent how many of that substance there are
• How would you increase the number of oxygen atoms on the left side of the methane combustion equation?

  By putting a 2 in front of $O_2$
• Why can't you use one and a half molecules of oxygen when balancing equations?

  Because we need to keep whole numbers
• How can you balance the number of hydrogens on the right side of the methane combustion equation?

  By increasing the number of water molecules from 1 to 2
• What is the process for balancing chemical equations?

  1. Count the number of each type of atom on both sides.
  2. Adjust the big numbers in front of compounds to balance the atoms.
  3. Ensure whole numbers are used.
  4. Double-check to confirm the equation is balanced.
• In the reaction of sulfuric acid and sodium hydroxide, what is the first element to balance?

  Sulfur
• How many sodium atoms are on the left side of the sulfuric acid and sodium hydroxide reaction?

  1 sodium
• How many sodium atoms are on the right side of the sulfuric acid and sodium hydroxide reaction?

  2 sodiums
• How do you balance the sodium atoms in the sulfuric acid and sodium hydroxide reaction?

  By putting a 2 in front of sodium hydroxide
• After balancing the sodium atoms, how many hydrogens and oxygens do you need to balance on the right side?


  Two more hydrogens and one more oxygen
• How do you balance the hydrogens and oxygens in the sulfuric acid and sodium hydroxide reaction?

  By adding one more water molecule to the right
• What should you do after you think you have balanced a chemical equation?

  Double-check to see if it's balanced
• What are the key components of a balanced chemical equation?

  • Reactants on the left side
  • Products on the right side
  • A single arrow indicating the reaction
  • Equal number of each type of atom on both sides