The military has experimented with lasers that produce very intense light when fluorine combines explosively with hydrogen. What is the balanced equation for this reaction?

A chemical reaction is a process where substances, known as reactants, are transformed into different substances, called products. During this transformation, bonds between atoms break and new bonds form, which results in a different arrangement of atoms. The conservation of mass principle tells us that in a closed system, the number of each type of atom must remain constant; hence, the same number of each atom must appear in the reactants and in the products. This principle is crucial when balancing chemical equations, where the number of atoms for each element must be equal on both sides.

Balancing a chemical equation is like solving a puzzle. You must ensure that the pieces, or atoms, fit together perfectly on both sides. It involves changing the coefficients (the numbers in front of the chemical formulas) to make sure the number of atoms of each element is the same on both sides of the equation without changing the actual formulas of the compounds or elements.

Diatomic molecules are a type of molecule that consists of two atoms of the same element bonded together. Seven elements naturally occur as diatomic molecules in their elemental forms, often remembered by the mnemonic 'BrINClHOF' (Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, and Fluorine).

Understanding the diatomic nature of certain molecules is critical when balancing chemical equations because you need to account for both atoms in the pair. For instance, hydrogen and fluorine in their gaseous states will exist as H2 and F2, respectively. This detail is fundamental in representing the correct molecular forms as reactants or products in an equation. It's also a common error point for students who may mistakenly count them as single atoms rather than as a pair that cannot be separated.

Stoichiometry is the part of chemistry that concerns the quantitative relationships between the reactants and products in a chemical reaction. The term comes from the Greek words 'stoicheion' (element) and 'metron' (measure). Stoichiometry allows chemists to predict the amounts of substances consumed and produced in a given reaction.

Using stoichiometry, one can calculate the exact amounts of reactants needed to react completely without excess, or determine how much product can be formed from a certain amount of reactant. This calculation is based on the balanced chemical equation, which provides the mole ratio (the ratio of the amount in moles of one substance to the amount in moles of another) necessary to ensure that atoms are conserved in the reaction. Stoichiometry is foundational for fields such as chemical engineering and pharmacology, where precise chemical compositions are crucial.

The reaction between hydrogen and fluorine that produces a very intense light is a highly exothermic reaction—which means it releases a significant amount of energy. The balanced chemical equation represents the stoichiometric relationship between these diatomic molecules.

The balanced equation for the reaction between hydrogen (H2) and fluorine (F2) is: \[2H_2 + F_2 \rightarrow 2HF\]This equation indicates that two hydrogen molecules (each made up of two hydrogen atoms) react with one fluorine molecule (made up of two fluorine atoms) to produce two molecules of hydrogen fluoride. The coefficients (2, 1, and 2) show the stoichiometric ratio of the reactants to the products. The hazardous nature of this reaction, with its potential to release intense energy, has led to interest in military applications, such as lasers, as well as in industrial chemistry for high-energy fuel sources.