Write and balance the word equatins

A chemical equation represents a chemical reaction. It shows the reactants (substances that start a reaction) and products (substances formed by the reaction). For example, in the reaction of hydrogen (H₂) with oxygen (O₂) to form water (H₂O), the chemical equation is:

However, this equation isn't balanced because the number of atoms for each element is not the same on both sides of the equation. A balanced equation obeys the Law of Conservation of Mass, which states that matter is neither created nor destroyed in a chemical reaction.

Balancing with inspection or trial and error method

This is the most straightforward method. It involves looking at the equation and adjusting the coefficients to get the same number of each type of atom on both sides of the equation.

Best for: Simple equations with a small number of atoms.

Process: Start with the most complex molecule or the one with the most elements, and adjust the coefficients of the reactants and products until the equation is balanced.

1. Count the number of H and O atoms on both sides. There are 2 H atoms on the left and 2 H atom on the right. There are 2 O atoms on the left and 1 O atom on the right.
2. Balance the oxygen atoms by placing a coefficient of 2 in front of H₂O:

Balancing with algebraic method

This method uses algebraic equations to find the correct coefficients. Each molecule's coefficient is represented by a variable (like x, y, z), and a series of equations are set up based on the number of each type of atom.

Best for: Equations that are more complex and not easily balanced by inspection.

Process: Assign variables to each coefficient, write equations for each element, and then solve the system of equations to find the values of the variables.

• 2 a = c
• 6 a = 2 d
• 2 b = 2c + d

• a = 1
• c = 2 a = 2
• d = 6 a / 2 = 4
• b = (2 c + d) / 2 = (2 * 2 + 3) / 2 = 3.5

Balancing with oxidation number method

Useful for redox reactions, this method involves balancing the equation based on the change in oxidation numbers.

Best For: Redox reactions where electron transfer occurs.

Process: identify the oxidation numbers, determine the changes in oxidation state, balance the atoms that change their oxidation state, and then balance the remaining atoms and charges.

1. Assign oxidation numbers:
   • Calcium (Ca) has an oxidation number of 0 in its elemental form.
   • Phosphorus (P) also has an oxidation number of 0 in its elemental form.
   • In Ca₃P₂, calcium has an oxidation number of +2, and phosphorus has an oxidation number of -3.
2. Identify the changes in oxidation numbers:
   • Calcium goes from 0 to +2, losing 2 electrons (reduction).
   • Phosphorus goes from 0 to -3, gaining 3 electrons (oxidation).
3. Balance the changes using electrons: Multiply the number of calcium atoms by 3 and the number of phosphorus atoms by 2.
4. Write the balanced Equation:

Balancing with ion-electron half-reaction method

This method separates the reaction into two half-reactions – one for oxidation and one for reduction. Each half-reaction is balanced separately and then combined.

Best for: complex redox reactions, especially in acidic or basic solutions.

Process: split the reaction into two half-reactions, balance the atoms and charges in each half-reaction, and then combine the half-reactions, ensuring that electrons are balanced.

Write down and balance half reactions: