Question

When solid red phosphorus, \(\mathrm{P}_{4},\) is burned in air, the phosphorus combines with oxygen, producing a choking cloud of tetraphosphorus decoxide. Write the unbalanced chemical equation for this reaction.

Short answer

The unbalanced chemical equation for the reaction between red phosphorus (P₄) and oxygen (O₂) to form tetraphosphorus decoxide is: \(P_4(s) + O_2(g) -> P_4O_{10}(s) \)

Step-by-step solution

Identify the reactants and products

The reactants for the reaction are solid red phosphorus (P₄) and oxygen (O₂). The product is tetraphosphorus decoxide.

Write the unbalanced chemical equation

To write the unbalanced chemical equation, write down the reactants and products with their respective chemical symbols or formulas, using an arrow "->" to indicate the direction of the reaction: P₄(s) + O₂(g) -> P₄O₁₀(s) This is the unbalanced chemical equation for the reaction of red phosphorus and oxygen to produce tetraphosphorus decoxide.

Key concepts

Balancing Chemical Equations

Understanding the process of balancing chemical equations is essential for mastering chemistry. The principle of conservation of mass dictates that the quantity of each element must remain the same before and after a chemical reaction. To balance a chemical equation, you start by writing it in its unbalanced form, which simply shows the reactants and products involved in the reaction. For example, the equation for the burning of red phosphorus in air is:

\[\begin{equation}\text{P}_4 (s) + \text{O}_2 (g) \rightarrow \text{P}_4\text{O}_{10} (s)ewlineewline\end{equation}\]
Here, '(s)' and '(g)' denote the physical states of the substances as solid and gas, respectively. To balance this equation, you would adjust the coefficients — numbers placed before the chemical formulas — to ensure that the number of atoms of each element is equal on both sides of the equation.
For instance, you would need to ensure that the quantity of oxygen atoms is equal in both the reactants and products. This may require trial and error and a basic understanding of stoichiometry, which is the measurement of the quantitative relationships, or ratios, between reactants and products in a chemical reaction. Balancing chemical equations is a foundational skill in chemistry that serves as a stepping stone to more complex concepts and calculations.

Reactants and Products

Every chemical reaction involves a transformation where initial substances, known as reactants, change into different substances called products. Recognizing reactants and products is the first step in deciphering chemical equations. The reactants are the starting materials that undergo a chemical change, while the products are the substances formed as a result of the reaction. In an equation, reactants are written on the left side, and products are on the right, separated by an arrow indicating the direction of the transformation.

In our example of burning red phosphorus, \[\begin{equation}\text{P}_4 (s)ewlineewline\end{equation}\]is the reactant along with \[\begin{equation}\text{O}_2 (g),ewlineewline\end{equation}\]and the product is\[\begin{equation}\text{P}_4\text{O}_{10} (s).ewlineewline\end{equation}\]In chemical equations, it is important to note the state of each substance, as it can affect the reaction. For example, gases might react differently compared to when they are dissolved in a solution (aqueous), or as solids or liquids. Understanding the role each reactant plays in a chemical reaction can further elucidate the reaction mechanism and influence how one approaches the balancing of the equation.

Chemical Reaction

A chemical reaction is the process by which one or more substances, the reactants, are converted into one or more different substances, the products. Reactions can be represented visually through chemical equations. These reactions may release or absorb energy, and occur in various forms including synthesis, decomposition, single replacement, and double replacement reactions. They also vary in terms of speed and the conditions required to take place, such as temperature, pressure, and the presence of catalysts.

Our illustrative example is a type of chemical reaction known as a synthesis or combination reaction, where two or more reactants combine to form a single product. The reaction between red phosphorus and oxygen to form tetraphosphorus decoxide can be represented by:\[\begin{equation}\text{P}_4 (s) + \text{O}_2 (g) \rightarrow \text{P}_4\text{O}_{10} (s)ewlineewline\end{equation}\]
Understanding the context and specific details of a chemical reaction is crucial. It includes knowing the reactants' physical state, the reaction conditions, and the composition of products. Learning how to unequivocally describe these reactions with balanced chemical equations is a valuable skill, which is fundamental for predicting the outcomes of reactions and for comprehending the principles of matter and its interactions.