Explain the different types of chemical equations: word, picture, and symbol equations, and provide an example of balancing the combustion of methane.

Here are the answers to the questions about chemical reactions and equations:

Chemical Reactions: Chemical Equations to Represent Reactions

• (b) What is a chemical reaction? A reaction or chemical reaction is a chemical change which results in the formation of new substances.
• (c) When a chemical equation is expressed in words, it is called a word equation.
• (d) When an equation is expressed using pictures or even models, it is a picture equation.
• (e) When symbols are used to represent chemical reaction, it is known as symbol equation.

Example: Methane Combustion

• Word equation (Equation in words): Methane + Oxygen $\rightarrow$ Carbon dioxide + Water
• Picture equation (Equation in pictures): 1 methane + 2 oxygen molecules $\rightarrow$ 1 carbon dioxide molecule + 2 water molecules
• Symbol equation (Equation in symbols): CH₄ + 2O₂ $\rightarrow$ CO₂ + 2H₂O
• Balanced chemical equation: CH₄ + 2O₂ $\rightarrow$ CO₂ + 2H₂O

Answer the following questions:

Example: Hydrogen Combustion

• Word equation (Equation in words): Hydrogen + Oxygen $\rightarrow$ Water
• Picture equation (Equation in pictures): 2 hydrogen molecules + 1 oxygen molecule $\rightarrow$ 2 water molecules
• Symbol equation (Equation in symbols): 2H₂ + O₂ $\rightarrow$ 2H₂O
• Balanced chemical equation: 2H₂ + O₂ $\rightarrow$ 2H₂O

Questions:

1. In the diagram above, what type of equations are represented by A, B and C?

   • A: Word equation
   • B: Picture equation
   • C: Symbol equation

2. In equation B, how many oxygen atoms are shown on the left of the equation?

   • There is one O₂ molecule, which contains 2 oxygen atoms.

3. How many carbon atoms (C) are on the right of the equation? (Referring to the methane combustion example)

   • There is one CO₂ molecule, which contains 1 carbon atom.

4. Write a word equation for: $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$

   • Hydrogen + Oxygen $\rightarrow$ Water