Project Number: 2023-1-PL01-KA220-SCH-000164042
UNIT 11: Vapor Pressure
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Education and Culture Executive Agency (EACEA). Neither the European Union nor EACEA can be held responsible for them.
Introduction
In this activity you will learn about vapor pressure and the factors affecting vapor pressure.
Source: canva.com
Learning Outcomes
- Students will be able to define vapour pressure as the pressure exerted by a vapour in equilibrium with its liquid.
- Students will be able to explain that vapour pressure changes depending on temperature.
- Students will be able to describe how intermolecular forces influence vapour pressure.
Source: canva.com
Steam engines played a critical role in the Industrial Revolution in the 18th century, radically transforming industrial and economic development. First developed by Thomas Newcomen (1712), the steam engine was used to pump water from mines.
- Design: low-pressure steam provided the piston motion.
Later, in 1765, James Watt’s innovations improved efficiency by optimizing energy use in steam engines.
- Impact: accelerated industrial production, reduced labor costs, and expanded transportation networks.
These developments played a fundamental role in the formation of modern industrial society, laying the foundations of today’s technological and economic structure.
Source: canva.com
Today, the power of steam is still utilized in thermal and geothermal power plants and in various fields of industry and manufacturing. So let's take a closer look at evaporation and vapor pressure. Evaporation and Vapor Pressure When the molecules on the surface of a liquid gain enough energy, they overcome the intermolecular forces that hold them together and escape into the gas phase. This process, known as evaporation, can occur at any temperature, not just at the boiling point. In a closed container or system, the gas molecules produced through evaporation exert a measurable pressure. This is called the vapor pressure, and it reflects the balance between the liquid and its vapour.
Source: canva.com
Learning Activity: Experimental Setup for Vapor Pressure Let’s design an experimental setup to better understand vapor pressure. Imagine you have a closed container from which all the air has been removed. You then place a small amount of water inside the container. Next, you gently heat the liquid and maintain it at a constant temperature. Under these conditions, you can observe how water molecules escape from the liquid surface, become vapor, and create a measurable vapor pressure within the closed system.
Source: canva.com
Equilibrium Vapor Pressure In a closed container that is not completely full, the liquid will gradually evaporate, and the empty space above it will begin to fill with its own vapor molecules. Over time, the container becomes saturated with these gaseous molecules. Some of the vapor molecules that lose energy during this process will condense, returning to the liquid state. At first, the rate of evaporation is greater than the rate of condensation. However, as more vapor accumulates, the two rates slowly approach each other. Eventually, they become equal, creating a state of dynamic equilibrium. The vapor pressure measured at this point—when the evaporation and condensation rates are equal at a constant temperature—is known as the equilibrium vapor pressure. In this state, there is no change in the liquid level or in the number of vapor particles in the container.
Source: canva.com
What do you think are the factors affecting the equilibrium vapor pressure? …………………………………………………………………………………………………………………………..………………………………………………………………..…………………………………………………………
Scan the QR code above to test the variables whose effect on the vapor pressure you want to measure.
At 25 °C , examine the vapor pressure of water, alcohol and salt water. Which of these liquids would you expect to boil first? Explain your opinion. ………………………………………………………………………………………………………………………………......
Evaluate the validity of the following claim based on the data you obtained as a result of the activity. "Boiling and vapor pressure are closely related. Boiling occurs at the temperature at which the vapor pressure of a liquid becomes equal to the atmospheric pressure of its environment. Therefore, the vapor pressure of a liquid varies depending on the atmospheric pressure." I think this claim is true/false. Because ……………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………
Source: canva.com
UNIT 11: Vapor Pressure
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Transcript
Project Number: 2023-1-PL01-KA220-SCH-000164042
UNIT 11: Vapor Pressure
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Education and Culture Executive Agency (EACEA). Neither the European Union nor EACEA can be held responsible for them.
Introduction
In this activity you will learn about vapor pressure and the factors affecting vapor pressure.
Source: canva.com
Learning Outcomes
Source: canva.com
Steam engines played a critical role in the Industrial Revolution in the 18th century, radically transforming industrial and economic development. First developed by Thomas Newcomen (1712), the steam engine was used to pump water from mines.
- Design: low-pressure steam provided the piston motion.
Later, in 1765, James Watt’s innovations improved efficiency by optimizing energy use in steam engines.- Impact: accelerated industrial production, reduced labor costs, and expanded transportation networks.
These developments played a fundamental role in the formation of modern industrial society, laying the foundations of today’s technological and economic structure.Source: canva.com
Today, the power of steam is still utilized in thermal and geothermal power plants and in various fields of industry and manufacturing. So let's take a closer look at evaporation and vapor pressure. Evaporation and Vapor Pressure When the molecules on the surface of a liquid gain enough energy, they overcome the intermolecular forces that hold them together and escape into the gas phase. This process, known as evaporation, can occur at any temperature, not just at the boiling point. In a closed container or system, the gas molecules produced through evaporation exert a measurable pressure. This is called the vapor pressure, and it reflects the balance between the liquid and its vapour.
Source: canva.com
Learning Activity: Experimental Setup for Vapor Pressure Let’s design an experimental setup to better understand vapor pressure. Imagine you have a closed container from which all the air has been removed. You then place a small amount of water inside the container. Next, you gently heat the liquid and maintain it at a constant temperature. Under these conditions, you can observe how water molecules escape from the liquid surface, become vapor, and create a measurable vapor pressure within the closed system.
Source: canva.com
Equilibrium Vapor Pressure In a closed container that is not completely full, the liquid will gradually evaporate, and the empty space above it will begin to fill with its own vapor molecules. Over time, the container becomes saturated with these gaseous molecules. Some of the vapor molecules that lose energy during this process will condense, returning to the liquid state. At first, the rate of evaporation is greater than the rate of condensation. However, as more vapor accumulates, the two rates slowly approach each other. Eventually, they become equal, creating a state of dynamic equilibrium. The vapor pressure measured at this point—when the evaporation and condensation rates are equal at a constant temperature—is known as the equilibrium vapor pressure. In this state, there is no change in the liquid level or in the number of vapor particles in the container.
Source: canva.com
What do you think are the factors affecting the equilibrium vapor pressure? …………………………………………………………………………………………………………………………..………………………………………………………………..…………………………………………………………
Scan the QR code above to test the variables whose effect on the vapor pressure you want to measure.
At 25 °C , examine the vapor pressure of water, alcohol and salt water. Which of these liquids would you expect to boil first? Explain your opinion. ………………………………………………………………………………………………………………………………......
Evaluate the validity of the following claim based on the data you obtained as a result of the activity. "Boiling and vapor pressure are closely related. Boiling occurs at the temperature at which the vapor pressure of a liquid becomes equal to the atmospheric pressure of its environment. Therefore, the vapor pressure of a liquid varies depending on the atmospheric pressure." I think this claim is true/false. Because ……………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………
Source: canva.com