What is a balanced chemical equation? Why should chemical equations be balanced?

The Law of Conservation of Mass is a fundamental principle in chemistry stating that mass is neither created nor destroyed in a chemical reaction. This means that the mass of the reactants must equal the mass of the products. To understand this, imagine the total number of atoms present before the reaction starts must be the same after the reaction is complete.
John Dalton, a renowned scientist, first proposed this idea in the early 19th century. His work helped lay the groundwork for modern chemistry.
For example, when we burn a piece of wood, the mass of the wood and the oxygen that reacts with it is equal to the mass of the ash, water vapor, and carbon dioxide produced.
Here's why this concept is crucial:

• If mass could be created or destroyed, it would violate the fundamental rules of chemistry and physics.
• Predicting the outcomes and quantities of substances in chemical reactions would become impossible.
• Ensures that we can balance chemical equations to accurately represent the involved substances.

A chemical reaction is a process where one or more substances (reactants) are transformed into one or more different substances (products). This transformation involves rearrangement of atoms and changes in the chemical bonds between them.
Let's break down this concept further:

• Reactants: The starting substances in a chemical reaction. For instance, hydrogen (\(H_2\)) and oxygen (\(O_2\)) are reactants in the reaction to form water.
• Products: The new substances formed as a result of the reaction. In the water formation example, water (\(H_2O\)) is the product.

Some common indicators of a chemical reaction include:

• Change in color
• Formation of a precipitate
• Emission of gas
• Release or absorption of energy

Remember, during a chemical reaction, the Law of Conservation of Mass always applies, meaning the mass of the reactants will always equal the mass of the products.

Balancing chemical equations is the method of making sure that the number of atoms of each element is the same on both the reactant and product sides of the equation. This is essential to adhere to the Law of Conservation of Mass.
Here are some steps to balance a chemical equation:

• Write down the unbalanced equation.
• Count the number of atoms for each element on the reactant side and the product side.
• Adjust coefficients (the numbers in front of molecules) to balance the number of atoms of each element on both sides.

For example, let's balance this equation: \(C_2H_6 + O_2 \rightarrow CO_2 + H_2O\)
Step-by-step:

• Start with carbon (C) atoms. We have 2 on reactant side in \(C_2H_6\) and 1 on product side in \(CO_2\). Adjust by changing the coefficient of \(CO_2\) to 2: \(C_2H_6 + O_2 \rightarrow 2CO_2 + H_2O\).
• Next, see hydrogen (H) atoms. We have 6 H in \(C_2H_6\) and 2 in \(H_2O\). Adjust by changing the coefficient of \(H_2O\) to 3: \(C_2H_6 + O_2 \rightarrow 2CO_2 + 3H_2O\).
• Now, balance oxygen (O) atoms. 2 from \(O_2\), 4 in \(2CO_2\), and 3 in \(3H_2O\). Adjust \(O_2\) coefficient to 7/2: \(C_2H_6 + 3.5O_2 \rightarrow 2CO_2 +3H_2O\).
• To eliminate fraction, multiply all coefficients by 2: \(2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O\).

By following these steps, we ensure that the equation is balanced, satisfying the Law of Conservation of Mass.