Question

In \(1968,\) before pollution controls were introduced, over 75 billion gallons of gasoline were used in the United States as a motor fuel. Assume an emission of oxides of nitrogen of 5 grams per vehicle mile and an average mileage of 15 miles per gallon of gasoline. How many kilograms of nitrogen oxides were released into the atmosphere in the United States in \(1968 ?\)

Short answer

The total nitrogen oxides released into the atmosphere in the United States in 1968 amounts to \(5.625*10^{9}\) kilograms.

Step-by-step solution

Convert Gallons to Miles

First calculate the total number of miles driven by taking the total gallons of gasoline used and multiply it with the average mileage per gallon. Therefore, \(75*10^9\) gallons * 15 miles/gallon = \(1.125*10^{12}\) miles.

Calculate Total Nitrogen Oxides Emission

Next, calculate the total nitrogen oxides emission. Since each vehicle mile produces 5 grams of nitrogen oxides, multiply the total miles driven from step 1 by the emission rate of 5 grams/mile, so \(1.125*10^{12}\) miles * 5 grams/mile = \(5.625*10^{12}\) grams of nitrogen oxides.

Convert Grams to Kilograms

Finally, because the problem asks for the solution in kilograms, convert the total from grams into kilograms. Since 1 kilogram equates to 1000 grams, divide the result from step 2 by 1000, leading to \((5.625*10^{12})/1000 = \(5.625*10^{9}\) kilograms.

Key concepts

Nitrogen Oxides Emissions

Nitrogen oxides ( ext{NO}_x), primarily composed of nitrogen dioxide (NO₂) and nitric oxide (NO), are significant atmospheric pollutants. These compounds play a crucial role in the formation of smog and acid rain, both of which have adverse effects on human health and the environment. Understanding emissions is crucial because they are released during the combustion of fossil fuels, such as gasoline, in vehicles.

Vehicles release NOₓ emissions primarily due to the high-temperature combustion processes in the engine, where nitrogen and oxygen from the air react. The 1968 case exemplifies this situation, where we assumed 5 grams of nitrogen oxides per mile. Given the scale of vehicle usage, even small emission rates per mile can accumulate into large quantities. Managing and minimizing these emissions is essential for reducing air pollution and protecting public health.

Environmental Chemistry

Environmental chemistry studies how chemical substances interact with the environment. It considers their effects on air, water, and soil, and how human activities influence these processes. Nitrogen oxides play a critical role in environmental chemistry due to their environmental impact.

The emission of NOₓ into the atmosphere can lead to the formation of ground-level ozone, a major component of smog that harms respiratory health. NOₓ compounds can also induce acid rain when they combine with water vapor. This acid rain can damage ecosystems, corroding buildings, and affecting aquatic habitats negatively.

Environmental chemists investigate these processes to develop technologies and policies aimed at reducing NOₓ emissions. Innovations such as catalytic converters in cars have diminished NOₓ releases dramatically. However, understanding and monitoring these emissions continue to be a focus area to ensure sustainable environmental management.

Unit Conversion in Chemistry

Unit conversion is a fundamental concept in chemistry that allows scientists and students to interpret and communicate measurements effectively. In the problem, several conversions were necessary to determine the amount of nitrogen oxides released.

First, we calculated the total miles driven by multiplying the volume of gasoline used (gallons) by the average distance (miles) each gallon covers. This initial conversion sets the basis for later calculations. Next, the emissions were calculated in grams based on the number of vehicle miles. Finally, grams were converted to kilograms because the problem specified the answer should be in this unit.

These conversions highlight a critical skill—manipulating and converting units to interpret real-world chemical phenomena accurately. Whether converting between weight, volume, or any other measurements, learning these skills assists in solving complex problems consistently.