Nitric oxide reacts with bromine and gives nitrosyl-bromide as per reaction given below: $$ 2 \mathrm{NO}_{(\mathrm{g})}+\mathrm{Br}_{2(\mathrm{~g})} \rightleftharpoons 2 \mathrm{NOBr}_{(\mathrm{g})} $$ When \(0.087\) mole of \(\mathrm{NO}\) and \(0.0437\) mole of \(\mathrm{Br}_{2}\) are mixed is a closed container at constant temperature, \(0.0518\) mole of NOBr is obtained at equilibrium. Calculate equilibrium amount of nitric oxide and bromine.

Understanding chemical equilibrium is pivotal for interpreting how chemical reactions occur in closed systems. At equilibrium, a chemical system has reached a state where the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in the concentration of reactants and products over time. However, this does not mean that the amounts of reactants and products are equal, but rather that their concentrations have stabilized to constant values.

When calculating equilibrium conditions, as in the exercise with nitric oxide and bromine, we examine the amounts of reactants and products that are present once the system has reached this state. These calculations often involve applying the stoichiometry of the reaction to relate the changes in reactants to the changes in products. It is a construct that allows chemists to predict the concentrations of various species within a reaction mixture after given amounts of reactants are mixed.

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. The exercise provided illustrates how stoichiometry is used to determine the amounts of nitric oxide and bromine at equilibrium. We use the balanced chemical equation to understand how the reactants combine and form products.

The equation indicates that two moles of NO react with one mole of Br₂ to produce two moles of NOBr. This is known as the mole ratio and is crucial for stoichiometric calculations. When we know the amount of one substance that reacts or is produced, we can use these mole ratios to calculate the corresponding amounts of the other substances involved in the reaction. Short, stoichiometry serves as the recipe for conducting and understanding the quantitative aspects of chemical reactions.

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Chemical reactions are represented by chemical equations, like the one in our exercise: 2 NO_(g) + Br_2(g) ⇌ 2 NOBr_(g). Such equations show the reactants (NO and Br₂) on the left side and the products (NOBr) on the right, depicting the rearrangement of atoms during the reaction.

Understanding chemical reactions involves appreciating that atoms and molecules interact in specific ways to form new compounds, often releasing or absorbing energy in the process. In the context of our example, nitric oxide and bromine react to form nitrosyl bromide, following conservation of mass and consistent with the principles of stoichiometry.

The mole concept is a method within chemistry for quantifying atoms, molecules, or other chemical entities. One mole is defined as exactly 6.022 x 10²³ (Avogadro's number) of chemical units, be they atoms, molecules, electrons, or other particles. In the example provided, moles provide a way to quantify how much of each reactant we have and how much product is produced.

0.087 moles of NO and 0.0437 moles of Br₂ initially are mixed. During the reaction to equilibrium, they yield 0.0518 moles of NOBr. Using the mole concept allows us to translate this information into concrete amounts of reactants that have reacted and to calculate how much remains unreacted at equilibrium, providing insight into the extent of the reaction and the composition of the final mixture.