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Ch.8 Gases
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
All textbooksTimberlake 13th EditionCh.8 GasesProblem 2c
Chapter 8, Problem 2c

Use the kinetic molecular theory of gases to explain each of the following:
c. You can smell the odor of cooking onions from far away.

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The kinetic molecular theory of gases states that gas particles are in constant, random motion and move in straight lines until they collide with other particles or the walls of their container.
When onions are cooked, volatile compounds are released into the air. These compounds are in the gas phase and begin to spread out due to their random motion.
According to the theory, gas particles diffuse, meaning they move from areas of higher concentration (near the cooking onions) to areas of lower concentration (farther away).
The random motion of gas particles allows them to travel through the air and mix with other gas particles, eventually reaching your nose even if you are far from the source.
This diffusion process is driven by the kinetic energy of the gas particles, which is proportional to the temperature. Higher temperatures during cooking increase the kinetic energy, speeding up the diffusion process and making the smell travel faster.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Kinetic Molecular Theory

The kinetic molecular theory explains the behavior of gases in terms of particles in constant motion. It posits that gas particles are small, widely spaced, and move randomly at high speeds. This motion allows gases to fill their containers and explains properties like pressure and temperature. Understanding this theory is essential for explaining how odors disperse in the air.
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Diffusion

Diffusion is the process by which molecules spread from areas of high concentration to areas of low concentration. In the context of gases, this means that the odor molecules from cooking onions move through the air, gradually mixing with the surrounding air. This phenomenon allows the smell to travel over distances, making it detectable even from afar.
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Concentration Gradient

A concentration gradient refers to the difference in the concentration of a substance between two areas. In the case of the onion smell, there is a higher concentration of odor molecules near the source and a lower concentration further away. The movement of these molecules down the concentration gradient is what allows the smell to be perceived at a distance, illustrating the principles of diffusion.
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Related Practice
Textbook Question

A tank contains oxygen (O2) at a pressure of 2.00 atm. What is the pressure in the tank in terms of the following units?

d. kPa

Textbook Question

A tank contains oxygen (O2) at a pressure of 2.00 atm. What is the pressure in the tank in terms of the following units?

b. lb/in.2

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Textbook Question

On a climb up Mount Whitney, the atmospheric pressure drops to 467 mmHg. What is the pressure in terms of the following units?

b. torr

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Textbook Question

Use the kinetic molecular theory of gases to explain each of the following:

c. Gases have low densities.

Textbook Question

Use the kinetic molecular theory of gases to explain each of the following:

b. The air in a hot-air balloon is heated to make the balloon rise.