Problem 101 - Chemistry Matter and Change

Question

Air Pollution Nitrogen oxide, which is present in urban air pollution, immediately converts to nitrogen dioxide as it reacts with oxygen. \begin{equation} \begin{array}{l}{\text { a. Write the balanced chemical equation for the forma- }} \\ {\text { tion of nitrogen dioxide from nitrogen oxide. }} \\\ {\text { b. What mole ratio would you use to convert from }} \\ {\text { moles of nitrogen oxide to moles of nitrogen dioxide? }}\end{array} \end{equation}

Step-by-Step Solution

Answer

a. The balanced chemical equation is \(2NO + O_2 \rightarrow 2NO_2\). b. The mole ratio is 1:1.

Step 1: Identify the Reactants and Products

The reaction involves nitrogen oxide (2NO) and oxygen (2O_2) forming nitrogen dioxide (2NO_2). The reactants are nitrogen oxide and oxygen, and the product is nitrogen dioxide.

Step 2: Write the Unbalanced Chemical Equation

Based on the identified reactants and products, the unbalanced equation is: \[ 2NO + O_2 \rightarrow 2NO_2 \] This shows that nitrogen oxide reacts with oxygen to form nitrogen dioxide.

Step 3: Balance the Chemical Equation

To balance the equation, ensure the number of each type of atom is equal on both sides. Start by balancing nitrogen atoms: two nitrogen atoms on each side. For oxygen, we have 2 from NO and then complete them as 2 from O_2 on the left to make 4 oxygen atoms needed on the right to match in 2 molecules of NO_2. The balanced formula is: \[ 2NO + O_2 \rightarrow 2NO_2 \]

Step 4: Determine the Mole Ratio

The balanced equation shows that 2 moles of NO are needed to produce 2 moles of NO_2. Thus, the mole ratio of nitrogen oxide to nitrogen dioxide is 2:2 or simplified, 1:1.

Key Concepts

Balanced Chemical Equation

In any chemical reaction, a balanced chemical equation is essential. This type of equation ensures that the same number of each type of atom appears on both sides. Balancing a chemical equation involves adjusting coefficients in front of the chemical formulas to maintain this equality. This practice is crucial because it follows the law of conservation of mass, indicating that matter cannot be created or destroyed.

Let's consider our example reaction, which involves nitrogen oxide (NO) reacting with oxygen (O₂) to form nitrogen dioxide (NO₂). The balanced equation for this reaction is:\[ 2NO + O_2 \rightarrow 2NO_2 \]Here, the number of nitrogen and oxygen atoms is equal on both sides of the equation. Understanding balanced chemical equations is important for predicting the amounts of reactants and products that will be needed or produced in a reaction.

• The equation follows the law of conservation of mass.
• It highlights the relationship between reactants and products.
• A balanced equation is fundamental for calculating mole ratios and other stoichiometric calculations.

Mole Ratio

Understanding mole ratios in a chemical equation is vital for quantitative chemistry calculations. The mole ratio is derived directly from the coefficients of the balanced chemical equation. It tells you how many moles of a reactant are required to react with another reactant, or how many moles of product are produced.

For our balanced equation \[ 2NO + O_2 \rightarrow 2NO_2 \], the coefficients indicate the mole ratios. We see from this reaction that 2 moles of NO react with 1 mole of O₂ to produce 2 moles of NO₂.

Key points about mole ratios include:

• Mole ratios come from the coefficients of a balanced equation.
• These ratios are essential for converting between moles of reactants and products using stoichiometry.
• In our example, the mole ratio of NO to NO₂ is 1:1, meaning one mole of NO produces one mole of NO₂.

Using mole ratios allows chemists to calculate how much of each substance is involved in a given chemical process.

Nitrogen Oxides Pollution

Nitrogen oxides (NOx), including nitrogen oxide (NO) and nitrogen dioxide (NO₂), are significant pollutants in urban areas. They mainly originate from vehicle emissions, fossil fuel combustion, and industrial processes.

These oxides contribute to several environmental issues:

• Smog Formation: They react with other compounds in sunlight, creating photochemical smog, which is harmful to human health.
• Acid Rain: They can combine with water vapor in the atmosphere to form nitric acid, leading to acid rain that affects water bodies, forests, and soils.
• Contribution to Respiratory Problems: NOx gases can irritate airways and worsen asthma conditions.

The presence of nitrogen oxides poses health risks, and it emphasizes the need for cleaner technologies and emissions controls in vehicles and industrial facilities to mitigate air pollution.

Environmental Chemistry

Environmental chemistry involves studying chemical processes that occur in the environment, including both natural and anthropogenic (human-made) activities. A key focus is understanding the impact of chemical substances on the environment and human health.

Nitrogen oxides are an excellent example of how environmental chemistry applies to real-world issues.

• Monitoring: Chemists monitor and measure nitrogen oxide levels as part of urban air quality assessments.
• Impact: Understanding their contribution to phenomena like smog and acid rain helps drive policies for cleaner technologies.
• Solutions: Environmental chemists explore technologies and strategies for reducing nitrogen oxide emissions to protect ecosystems and public health.

Environmental chemistry plays a crucial role in developing new methods and regulations to address pollution and sustainability challenges.