Question

Consider the incomplete molecular-level diagram of the following reaction: $$ \mathrm{H}_{2}(g)+\mathrm{I}_{2}(g) \longrightarrow 2 \mathrm{HI}(g) $$ Complete this diagram to show the products expected for this reaction.

Short answer

In this reaction, one Hydrogen molecule \(H_{2}\) and one Iodine molecule \(I_{2}\) combine to form two molecules of Hydrogen Iodide \(2HI\), each composed of one Hydrogen atom and one Iodine atom.

Step-by-step solution

Understanding the reaction

The given reaction is \(H_{2}(g) + I_{2}(g) \longrightarrow 2HI(g)\). This is a chemical reaction between hydrogen (H2) and iodine (I2) to form hydrogen iodide (HI). Always remember, the numbers in front of the molecules indicate the number of molecules involved in the reaction.

Representation of Reactants

Here, hydrogen (H2) and iodine (I2) are the reactants. Both of these are diatomic molecules, which means they come in pairs. So, Hydrogen is represented by two hydrogen atoms (H-H) and Iodine by two iodine atoms (I-I).

Resultant product

The result of the reaction is the formation of hydrogen iodide (HI). According to the reaction, one molecule of Hydrogen (H2) combines with one molecule of Iodine (I2) to form two molecules of Hydrogen Iodide (HI). This shows that one H from the (H-H) will combine with one I from the (I-I) to form HI. The same will happen with the other pair. Therefore, '2HI' is equivalent to H-I and H-I.

Key concepts

Molecular-Level Diagrams

When discussing chemical reactions, molecular-level diagrams provide a visual interpretation of the molecules involved. They help by illustrating how molecules are structured and how they interact during a reaction.
In the given equation, we have two reactants, \(H_2\) and \(I_2\), which are gases. These reactants are shown as pairs of atoms at the molecular level — for example, hydrogen is represented by two connected hydrogen atoms. This visual method can make it easier to understand the pairing and rearrangement of atoms to form products.
Completing a molecular-level diagram typically involves drawing the reaction process out. This means starting with the reactants in their diatomic form and showing how they combine to form the products, ensuring that the number of atoms on each side of the equation is balanced.
Here are some steps you may follow:

• Begin by drawing the reactants \(H_2\) and \(I_2\) each as pairs of connected atoms.
• Show the breaking of bonds in the reactants as they transform into products.
• Finally, pair the atoms to generate the product, which in this case is \(HI\) shown twice.

Using these diagrams can boost comprehension by visually representing what happens during the reaction process.

Reactants and Products

Every chemical reaction involves reactants and products. Reactants are the starting substances that undergo changes in the reaction.
In the equation \(H_2(g) + I_2(g) \rightarrow 2HI(g)\), the reactants are \(H_2\) and \(I_2\). These substances react with each other to form new substances, known as products. Here, hydrogen iodide (\(HI\)) is the product.
The transformation can be thought of as a rearrangement of atoms:

• Reactants \(H_2\) and \(I_2\) break their initial bonds.
• Atoms from these molecules re-bond to form products, which are two \(HI\) molecules.

It is crucial to appreciate that the number of each type of atom is conserved during the reaction. This principle, known as the law of conservation of mass, indicates that atoms are neither created nor destroyed; they are merely rearranged from reactants to products.

Diatomic Molecules

Diatomic molecules are molecules composed of only two atoms, of either the same or different chemical elements. In the context of our reaction \(H_2 + I_2 \rightarrow 2HI\), both hydrogen and iodine are diatomic molecules.
Some of the most common diatomic molecules in nature include

• Hydrogen \(H_2\)
• Oxygen \(O_2\)
• Nitrogen \(N_2\)
• Chlorine \(Cl_2\)

These molecules are often stable in this diatomic form because of how they share electrons to fill their outer shell — this process is known as covalent bonding.
Understanding diatomic molecules helps in predicting how elements will behave in reactions, such as the formation of \(HI\) from \(H_2\) and \(I_2\). Since both reactants are naturally found as pairs of atoms, molecular diagrams portraying these pairs are foundational in depicting the actual chemical processes occurring during the reaction.