Predicting Outcomes When gasoline burns in an automobile engine, nitric oxide is formed from oxygen and nitrogen. Nitric oxide is a major air pollutant. High temperatures, such as those found in a combustion engine, are needed for the following reaction: \(\mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) \rightleftarrows 2 \mathrm{NO}(g)\) Kfor the reaction is 0.01 at \(2000^{\circ} \mathrm{C} .\) If 4.0 \(\mathrm{mol}\) of \(\mathrm{N}_{2}\) 0.1 \(\mathrm{mol}\) of \(\mathrm{O}_{2},\) and 0.08 \(\mathrm{mol}\) of NO are placed in a 1.0 -L vessel at \(2000^{\circ} \mathrm{C}\) , predict which reaction will be favored.

The reaction quotient, Q, is an important concept when discussing chemical equilibrium. It helps us determine the direction in which a reaction will proceed to reach equilibrium. Q is calculated using the initial concentrations of the reactants and products.
The formula for Q is the same as the one used to calculate the equilibrium constant, K, but it uses the initial concentrations:
\[\text{Q} = \frac{[\text{Products}]^{coefficients}}{[\text{Reactants}]^{coefficients}}\]
In the given exercise:
\[\text{Q} = \frac{[\text{NO}]^2}{[\text{N}_2][\text{O}_2]}\]
By plugging in the initial concentrations, we found that Q = 0.016. This tells us whether the system is already at equilibrium or needs to shift to reach it. Since Q (0.016) is greater than K (0.01), the reaction will shift toward the reactants to achieve equilibrium. This helps ensure the correct amounts of reactants and products are present based on the conditions given.

The equilibrium constant, K, is a crucial value in chemistry that represents the ratio of the concentrations of products to reactants at equilibrium. For the reaction:
\[\text{N}_2(g) + \text{O}_2(g) \rightleftarrows 2 \text{NO}(g)\]
the equilibrium constant expression is:
\[\text{K} = \frac{[\text{NO}]^2}{[\text{N}_2][\text{O}_2]}\]
K is temperature-dependent and gives insight into the position of equilibrium. In the given exercise, K is 0.01 at 2000°C. This small value of K indicates that, at equilibrium, the concentration of reactants is much higher than that of the products. Since the initial Q (0.016) in our example is greater than K (0.01), the reaction is not at equilibrium and will shift towards the reactants to reach the equilibrium state. Understanding K helps predict how a change in conditions or concentrations can affect the direction the reaction takes.

Combustion reactions are a type of chemical reaction where a substance combines with oxygen to release energy. These reactions are prevalent in processes such as burning fuel in car engines.
The given exercise involves the combustion reaction:
\[\text{N}_2(g) + \text{O}_2(g) \rightleftarrows 2 \text{NO}(g)\]
High temperatures, like those in an engine, are necessary for the formation of nitric oxide (NO) from nitrogen (N\text{N}_2) and oxygen (O_2). While producing energy is the primary goal, these reactions can also create unwanted byproducts, like NO, which act as air pollutants.
Understanding combustion reactions allows us to see how these processes contribute to both energy production and environmental impact. By studying equilibrium concepts in combustion reactions, we can improve efficiency and mitigate harmful emissions.

Air pollutants are harmful substances released into the atmosphere, negatively affecting health and the environment. In our exercise, nitric oxide (NO) is identified as a major air pollutant.
NO is formed during high-temperature combustion processes, such as in car engines. It can react with other compounds in the atmosphere to form nitrogen dioxide (NO2) and contribute to smog and acid rain.
Major sources of air pollutants include:

• Vehicle emissions
• Industrial processes
• Burning fossil fuels

Understanding the reaction mechanisms and equilibrium in these processes can help develop strategies to reduce the formation of such pollutants.
By controlling the conditions under which these reactions occur, we can minimize the amount of NO and other pollutants emitted into the air, thus improving air quality and reducing environmental impact.