2.1.3 Chemical equations

• In the equation 2H₂(g) + O₂(g) → 2H₂O(l), water is the product

  True
• State symbols in chemical equations indicate the physical state
• Reactants are always found on the right side of the arrow in a chemical equation

  False
• Reactants are located on the left
• What do coefficients in a balanced chemical equation represent?

  Relative amounts
• In the equation 2H₂(g) + O₂(g) → 2H₂O(l), water is the product
• A chemical equation is a symbolic representation of a chemical reaction
• What do coefficients in a chemical equation balance?

  Law of conservation of mass
• Match the state symbols with their meanings:

  (g) ↔️ Gas

  (l) ↔️ Liquid

  (s) ↔️ Solid

  (aq) ↔️ Aqueous solution
• What should be ensured when balancing a chemical equation?

  Number of atoms is equal
• What is the balanced equation for the combustion of methane?

  CH₄ + 2O₂ → CO₂ + 2H₂O
• What is the purpose of state symbols in a chemical equation?

  Indicate physical state
• In a chemical equation, reactants are on the left side of the arrow.


  True
• Where are reactants found in a chemical equation?

  Left side
• Reactants are substances that start a chemical reaction
• What is the purpose of reactants in a chemical reaction?

  To initiate the reaction
• A chemical equation is a symbolic representation of a chemical reaction
• What do coefficients in a chemical equation represent?

  Relative amounts of substances
• Coefficients in a chemical equation balance the equation to follow the Law of Conservation of Mass
• Steps to balance chemical equations

  1️⃣ Identify reactants and products and count atoms

  2️⃣ Start with the most complex molecule

  3️⃣ Adjust coefficients to balance one element at a time

  4️⃣ Check for balance and iterate if needed
• What is the balanced equation for the combustion of methane (CH₄)?

  CH₄ + 2O₂ → CO₂ + 2H₂O
• What is the first step in writing a balanced chemical equation?

  Identify reactants and products
• In a combustion reaction, oxygen is always balanced as the final element
• Steps for balancing a combustion reaction

  1️⃣ Balance carbon

  2️⃣ Balance hydrogen

  3️⃣ Balance oxygen
• Write the unbalanced equation for the combustion of methane.

  CH₄ + O₂ → CO₂ + H₂O
• The final balanced equation for the combustion of methane is CH₄ + 2O₂ → CO₂ + 2H₂O


  True
• What is a skeletal equation in chemistry?

  Reactants and products only
• Match the equation type with an example:

  Skeletal Equation ↔️ H₂(g) + O₂(g) → H₂O(l)

  Balanced Equation ↔️ 2H₂(g) + O₂(g) → 2H₂O(l)
• Skeletal equations are used to perform stoichiometric calculations.

  False
• In a chemical equation, the arrow (→) separates reactants from products
• Reactants are found on the left side of the arrow in a chemical equation.
• What are reactants in a chemical reaction?

  Substances that start the reaction
• Products in a chemical equation are found on the left side of the arrow.

  False
• A chemical equation is a symbolic representation of a chemical reaction
• What do coefficients in a chemical equation indicate?

  Relative amounts
• Match the element of a chemical equation with its description:

  Reactants ↔️ Substances that start the reaction

  Products ↔️ Substances formed after the reaction

  Coefficients ↔️ Numbers that balance the equation

  State Symbols ↔️ Indicate physical state
• What is the role of reactants in a chemical reaction?

  Start the reaction
• Steps for balancing chemical equations

  1️⃣ Write the unbalanced equation

  2️⃣ Count the number of atoms of each element on both sides

  3️⃣ Adjust the coefficients to balance the atoms

  4️⃣ Check if the equation is balanced
• The arrow in a chemical equation indicates the direction of the reaction


  True
• What are the reactants in the reaction to form water?

  Hydrogen and oxygen