Question

The conversion of one air pollutant, nitrogen monoxide, produced in vehicle engines, into another pollutant, nitrogen dioxide, occurs when nitrogen monoxide reacts with molecular oxygen in the air. Write the balanced equation for this reaction.

Short answer

The balanced chemical equation for the reaction is: 2 NO + O2 → 2 NO2.

Step-by-step solution

Write the unbalanced equation

Start by expressing the reaction with an unbalanced chemical equation, using the chemical formulas for the reactants and products. The reactants are nitrogen monoxide (NO) and molecular oxygen (O2), and the product is nitrogen dioxide (NO2). The unbalanced equation is: NO + O2 → NO2.

Balance the oxygen atoms

Balance the oxygen atoms first as they are in both reactants. Since there are two oxygen atoms in O2 and only one in NO2, you should put a coefficient of 2 in front of NO2 to balance the oxygen atoms: NO + O2 → 2 NO2.

Balance the nitrogen atoms

Now, balance the nitrogen atoms. There are 2 nitrogen atoms in the products since you have 2 molecules of NO2. Put a coefficient of 2 in front of NO to balance the nitrogen: 2 NO + O2 → 2 NO2.

Verify the balanced equation

Verify that both sides of the equation have the same number of atoms of each element. The balanced equation has 2 nitrogen atoms and 2+2=4 oxygen atoms on both sides, confirming that the equation is balanced: 2 NO + O2 → 2 NO2.

Key concepts

Nitrogen Monoxide Pollution

Nitrogen monoxide, also known as nitric oxide (NO), is a significant air pollutant which is primarily produced by vehicle engines and various industrial processes. This colorless gas plays a crucial role in the formation of smog and acid rain. It can have various adverse health effects, such as respiratory problems, as it reacts with oxygen and other substances in the atmosphere to form more toxic compounds like nitrogen dioxide (NO2).

Understanding the sources and Environmental Interaction of nitrogen monoxide is essential for developing strategies to reduce pollution levels. Vehicle emissions controls, such as catalytic converters, have been effective in decreasing the release of nitrogen monoxide by converting it into less harmful substances before expelling it into the atmosphere. Despite these efforts, nitrogen monoxide pollution remains a concern especially in urban areas with high traffic.

Chemical Reaction Steps

A chemical reaction involves the transformation of reactants into products, which occurs in a series of steps. The first step is to write the unbalanced equation that represents the reactants and products in their molecular forms. In the case of nitrogen monoxide reacting with oxygen, the initial, unbalanced reaction is written as NO + O2 → NO2. This step sets the stage for the subsequent balancing of the equation.

Next comes the balancing of individual atoms in the equation, often starting with the most complex molecule or the element that appears in fewer substances in the reaction. In our example, we begin by balancing the oxygen atoms, followed by the nitrogen atoms, leading to the equation 2 NO + O2 → 2 NO2. The final verification confirms that both sides of the reaction have an equal number of atoms for each element, highlighting the conservation of matter in the reaction.

Stoichiometry

Stoichiometry is a branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. By utilizing the coefficients from the balanced chemical equation, stoichiometry allows scientists and engineers to calculate the amounts of substances consumed and produced.

For the reaction between nitrogen monoxide and oxygen, the balanced equation 2 NO + O2 → 2 NO2 provides the molar relationships necessary for these calculations. It indicates that two moles of nitrogen monoxide react with one mole of oxygen to produce two moles of nitrogen dioxide. This stoichiometric relationship is crucial for predicting the quantities of pollutants formed and for designing processes to reduce the emissions of harmful substances like NO and NO2 in the environment.