Question

What is the difference between coefficients and subscripts in a balanced chemical equation?

Short answer

Coefficients indicate the number of molecules; subscripts show the number of atoms in a molecule.

Step-by-step solution

Understanding Coefficients

In a chemical equation, coefficients are the numbers placed in front of the chemical formulas. They indicate the number of molecules or moles of each substance involved in the reaction. For example, in the equation \(2H_2 + O_2 \rightarrow 2H_2O\), the coefficient '2' before \(H_2\) and \(H_2O\) indicates there are two molecules of hydrogen and two molecules of water.

Understanding Subscripts

Subscripts in a chemical formula are the small numbers found immediately after and slightly below element symbols. They indicate the number of atoms of that element in one molecule of the compound. In the formula \(H_2O\), the subscript '2' means there are two hydrogen atoms in each molecule of water.

Roles in Balanced Equations

In a balanced chemical equation, coefficients are used to ensure that the number of each type of atom is equal on both sides of the equation, maintaining the law of conservation of mass. Subscripts, on the other hand, are part of the chemical formula and cannot be changed without altering the identity of the substance.

Example Illustration

Consider the balanced equation \(2H_2 + O_2 \rightarrow 2H_2O\). Coefficients ensure there are four hydrogen atoms and two oxygen atoms on both sides of the equation. Subscripts within \(H_2\) and \(H_2O\) simply denote hydrogen's characteristics in molecular hydrogen and water respectively, remaining consistent throughout.

Key concepts

Coefficients

Coefficients in a chemical equation are crucial as they tell us the number of molecules or moles of each substance participating in a reaction. They are the large numbers placed in front of chemical formulas. For example:

• In the equation \(2H_2 + O_2 \rightarrow 2H_2O\), the coefficient '2' before \(H_2\) indicates there are two molecules of hydrogen gas reacting with one molecule of oxygen gas.
• The same coefficient '2' before \(H_2O\) tells us there are two molecules of water produced.

Coefficients help us to balance the chemical equation and provide a clear depiction of the reaction dynamics. Changing coefficients alters the quantities but keeps the chemical identity intact.

Subscripts

Subscripts are a little different from coefficients and play a distinct role in chemical formulas. These are the small numbers written right after and below the element symbols, signifying the number of atoms of each element in a single molecule of a compound. For example:

• In \(H_2O\), the subscript '2' following hydrogen \(H\) means each molecule of water has two hydrogen atoms.
• If you have \(CO_2\), the subscript '2' tells there are two oxygen atoms in each molecule of carbon dioxide.

It's important to remember that subscripts are part of the molecular structure and cannot be changed. Adjusting subscripts would lead to a different substance altogether, which is why they remain constant during balancing.

Law of Conservation of Mass

The law of conservation of mass is a fundamental principle in chemistry stating that mass cannot be created or destroyed in a chemical reaction. This means that the total mass of reactants must equal the total mass of products.
In a chemical equation, every atom that starts on the reactant side must appear on the product side. No atoms are lost or gained; they are simply rearranged. For example:

• In the balanced equation \(2H_2 + O_2 \rightarrow 2H_2O\), there are four hydrogen atoms and two oxygen atoms on both sides.
• This reflects the law of conservation of mass as each side of the equation contains the same number and type of atoms.

Balancing equations helps us uphold this law, ensuring the chemical reaction is accurately represented.

Balanced Chemical Equations

A balanced chemical equation is one where the number of atoms for each element is equal on both sides of the equation. This is essential for accurately depicting the chemical reaction, in respect to the conservation laws.
To achieve a balanced equation, one must adjust the coefficients so that:

• The total number of atoms of each element is the same on the reactant and product sides.
• Chemical species are not altered during the balancing process.

For instance, consider \(2H_2 + O_2 \rightarrow 2H_2O\). Here, the equation is balanced since there are equivalent hydrogen and oxygen atoms on both sides. Balanced chemical equations ensure that the reaction abides by the law of conservation of mass and offers a correct description of the matter transformation in chemical processes.