When iron rusts, solid iron reacts with gaseous oxygen to form solid iron(III) oxide. Write a balanced chemical equation for this reaction.

Understanding chemical reactions is fundamental in the study of chemistry. A chemical reaction involves the transformation of one or more substances, the reactants, into one or more different substances, the products. This process involves breaking and forming chemical bonds which requires energy changes. The reaction between iron and oxygen to form iron(III) oxide, commonly known as rusting, is a type of chemical reaction known as a synthesis reaction, where simple substances combine to form a more complex substance.

When writing the chemical equation for a reaction, the reactants are listed on the left side of the equation and the products on the right, separated by an arrow indicating the direction of the transformation. For instance, in the reaction between iron (Fe) and oxygen (O₂), the equation starts as Fe + O₂ → Fe₂O₃ before it is balanced.

The law of conservation of mass requires that in a closed system, mass must remain constant over time. This law is the driving force behind balancing chemical equations. To respect this principle, the same number of each type of atom must exist on both sides of the equation after the reaction as before. This means adjustments are often necessary to equalize the number of atoms of each element in the reactants and products, which is achieved by changing the coefficients (the numbers in front) of the chemical formulas.

The concept of stoichiometry arises from the Greek words 'stoicheion' (element) and 'metron' (measure), and it deals with the quantitative aspect of chemical reactions. It is the calculation of reactants and products in chemical reactions in chemistry. Stoichiometry allows chemists to make predictions about the outcomes of chemical reactions, including what amount of products to expect when reactants are combined and how much of each reactant is needed to create a given amount of product.

To perform stoichiometric calculations, the chemical equation must be balanced. In the example of rusting iron, stoichiometry dictates how many moles of iron will react with oxygen to form a specific amount of iron(III) oxide. The balanced equation 4 Fe + 3 O₂ → 2 Fe₂O₃ illustrates that 4 moles of iron react with 3 moles of oxygen to produce 2 moles of iron(III) oxide. Understanding stoichiometric coefficients (the number in front of the substances) is crucial for these calculations, as they indicate the proportional amounts of each substance involved in the reaction.

A common challenge with stoichiometry for students is dealing with fractional coefficients, which cannot be used in a final balanced equation. Multiplying all coefficients by the smallest common multiple to obtain whole numbers, as shown in the step-by-step solution, is a method to overcome this issue.

Chemical formulas represent the types and numbers of atoms that make up a substance, providing a wealth of information in a concise format. For instance, in Fe₂O₃, the formula for iron(III) oxide, the subscript '2' indicates that there are two atoms of iron, while the subscript '3' indicates three atoms of oxygen in the compound.

Element symbols from the periodic table are used to denote the kinds of atoms present. Subscripts tell us how many atoms of each element are in the compound, and coefficients (placed in front of the formulas) indicate how many molecules or units of that substance are involved.

In the context of balancing equations, the chemical formulas must be correct, and they are not altered to balance the equation – only the coefficients are adjusted. For instance, the oxygen molecule is written as O₂ and not just O, because oxygen exists naturally as diatomic molecules. Mistakes in writing chemical formulas can lead to incorrect balance in chemical equations, resulting in flawed stoichiometric calculations. Hence, a proper understanding of chemical formulas is essential when solving chemical equations and conducting stoichiometric analyses.