Question

Write an unbalanced equation to represent each of the following reactions: (a) nitrogen and oxygen react to form nitrogen dioxide, (b) dinitrogen pentoxide reacts to form dinitrogen tetroxide and oxygen, (c) ozone reacts to form oxygen, (d) chlorine and sodium iodide react to form iodine and sodium chloride, and (e) magnesium and oxygen react to form magnesium oxide. (f) Balance equations (a)-(e).

Short answer

Balanced equations: (a) ${\text{N}}_2+2{\text{O}}_2\to 2{\text{NO}}_2$; (b) $2{\text{N}}_2{\text{O}}_5\to 2{\text{N}}_2{\text{O}}_4+{\text{O}}_2$; (c) $2{\text{O}}_3\to 3{\text{O}}_2$; (d) ${\text{Cl}}_2+2\text{NaI}\to {\text{I}}_2+2\text{NaCl}$; (e) $2\text{Mg}+{\text{O}}_2\to 2\text{MgO}$.

Step-by-step solution

Write the Unbalanced Equations for Each Reaction

For each chemical reaction, write the skeleton equation using chemical formulas:(a) Nitrogen and oxygen react to form nitrogen dioxide: $${\text{N}}_2+{\text{O}}_2\to {\text{NO}}_2$$(b) Dinitrogen pentoxide reacts to form dinitrogen tetroxide and oxygen: $${\text{N}}_2{\text{O}}_5\to {\text{N}}_2{\text{O}}_4+{\text{O}}_2$$(c) Ozone reacts to form oxygen: $${\text{O}}_3\to {\text{O}}_2$$(d) Chlorine and sodium iodide react to form iodine and sodium chloride: $${\text{Cl}}_2+\text{NaI}\to {\text{I}}_2+\text{NaCl}$$(e) Magnesium and oxygen react to form magnesium oxide: $$\text{Mg}+{\text{O}}_2\to \text{MgO}$$

Balance Equation (a)

For the reaction ${\text{N}}_2+{\text{O}}_2\to {\text{NO}}_2$, balance the number of nitrogen and oxygen atoms:- Three nitrogen atoms on each side by balancing with 2 nitrogen molecules and 2 nitrogen dioxide molecules.- Balance oxygen: six oxygen atoms, using 3 oxygen molecules.Balanced equation:$${\text{N}}_2+2{\text{O}}_2\to 2{\text{NO}}_2$$

Balance Equation (b)

For the reaction ${\text{N}}_2{\text{O}}_5\to {\text{N}}_2{\text{O}}_4+{\text{O}}_2$:- Start by balancing nitrogen: there are 2 nitrogen atoms on both sides.- Balance oxygen: 5 oxygen atoms on the left, so write as: 2 dioxides and 1 oxygen molecule.Balanced equation:$$2{\text{N}}_2{\text{O}}_5\to 2{\text{N}}_2{\text{O}}_4+{\text{O}}_2$$

Balance Equation (c)

For the reaction ${\text{O}}_3\to {\text{O}}_2$:- Balance oxygen atoms. Three atoms of oxygen produce two molecules.- Write as 2 ozone. That allows us to work with 3 oxygen molecules.Balanced equation:$$2{\text{O}}_3\to 3{\text{O}}_2$$

Balance Equation (d)

For the reaction ${\text{Cl}}_2+\text{NaI}\to {\text{I}}_2+\text{NaCl}$:- Balance iodine: add 2 Na molecules to balance with the produced iodine.- Balance chlorine and sodium on left and right sides: use similar quantification.Balanced equation:$${\text{Cl}}_2+2\text{NaI}\to {\text{I}}_2+2\text{NaCl}$$

Balance Equation (e)

For the reaction $\text{Mg}+{\text{O}}_2\to \text{MgO}$:- Balance magnesium: add 2 Mg atoms.- Utilize 2 MgO on the right to complete equation.Balanced equation:$$2\text{Mg}+{\text{O}}_2\to 2\text{MgO}$$

Key concepts

Balancing Chemical Equations

Balancing chemical equations is a crucial step in understanding chemical reactions. It ensures that the law of conservation of mass, which states that mass is neither created nor destroyed in a chemical reaction, is upheld. To balance an equation, you need to have the same number of each type of atom on both sides of the equation.

For example, consider the reaction: ${\text{N}}_2+{\text{O}}_2\to {\text{NO}}_2$. Initially, the equation has an unequal number of atoms on both sides. By adjusting the coefficients (the numbers in front of each compound), this reaction can be balanced as ${\text{N}}_2+2{\text{O}}_2\to 2{\text{NO}}_2$.

It's like playing a game of balance where all atom types must be in equal numbers before and after the reaction. Understanding this concept not only satisfies curiosity but is vital for accurate calculations in chemical analysis.

Unbalanced Chemical Equations

Unbalanced chemical equations, often called skeleton equations, are representations of reactions that have not yet been adjusted to reflect the conservation of mass. These equations provide only the starting materials (reactants) and end products (products) without the necessary coefficients to equalize the atoms involved.

Take the equation $\text{Mg}+{\text{O}}_2\to \text{MgO}$ as an example. This equation, as it stands, is unbalanced since there are unequal numbers of magnesium and oxygen atoms on each side. Recognizing an unbalanced equation is crucial because it acts as the first step towards solving and understanding a chemical reaction.

Unbalanced equations are the basis from which you can derive balanced equations that adhere to the conservation laws. Learning to identify and rectify these is an essential skill in chemistry.

Chemical Reactions

Chemical reactions describe the process where reactants transform into products, involving the rearrangement of atoms. Each reaction is unique and is identified by a chemical equation that summarizes which substances react and what they transform into.

For instance, when magnesium reacts with oxygen to form magnesium oxide, it is written as $2\text{Mg}+{\text{O}}_2\to 2\text{MgO}$. This is not just a simple rearrangement of letters but a fundamental change in the chemical properties.

Chemical reactions can vary from simple transformations, like decomposition, to more complex ones like redox reactions. Understanding the types of reactions allows chemists to predict the products and conditions necessary for the reactions. It opens the door to applications in many fields, from industrial manufacturing to pharmaceuticals.

Stoichiometry

Stoichiometry is the study of quantitative relationships in chemical reactions. It uses the balanced chemical equation to determine the proportions of reactants and products involved. This process relies heavily on the concept of the mole, a standard chemical measurement indicating a specific number of atoms or molecules.

For example, with the balanced reaction $2\text{Mg}+{\text{O}}_2\to 2\text{MgO}$, stoichiometry allows us to calculate how much oxygen is needed to react completely with a given amount of magnesium, or how much magnesium oxide is produced.

Through stoichiometry, chemists can scale reactions up or down, predicting yields, or resource needs, which is invaluable in both laboratory settings and industry. It forms the critical link between theoretical equations and practical experiments, making it fundamental to the discipline of chemistry.