13.5 Phase Changes

As you change the volume, add or remove heat, change gravity, and more, you can see what happens in a box.

The properties of the gas vary in relation to each other, if you measure the temperature and pressure.

We have considered the behavior of ideal gases.

At high temperatures, real gases are ideal.
The interactions between the molecule and their volumes cannot be ignored at lower temperatures.
It becomes a solid when a liquid is cooled down.
The volume is never zero because of the volume of the molecule.

The ideal gas behavior is represented by the straight line part of the graph, which shows the temperature and volume in relation to each other.

At the liquefaction point, the volume decreases dramatically when the gas becomes liquid.
The volume never becomes zero once the substance is solid.

High pressure can cause a gas to change phase.

Carbon dioxide is a gas at room temperature and atmospheric pressure, but becomes a liquid under high pressure.
The liquid carbon dioxide will form a snow-like substance at the temperature if the pressure is reduced.

Liquid nitrogen can be in a liquid phase.

At atmospheric pressure, it boiled at 77 K.

It is used to help cool down the wires that carry the electronic sensors.

It is possible to freeze and painlessly remove warts and other growths from the skin.

The ideal gas law describes the relationship between the pressure and volume of the substance.

As the pressure increases, the volume of the gas will decrease.

The ideal-gas behavior at various fixed temperatures is called isotherms.

The curves look less like hyperbolas at lower temperatures.
Above which liquid can't be found.
The gas will have a density of a liquid but not condense at high pressure.
Carbon dioxide can't be liquefied at a temperature higher than.

The lower curves are not hyperbolas because the gas is no longer an ideal gas.

The termvapor refers to the gas phase when it is below the boiling temperature.

The thermal properties of substances can be seen in the plots of pressure and temperatures.

The phase of water can be determined using the graph if you know the pressure and temperature.
The solid lines--boundaries between phases--indicate temperatures and pressures at which the phases coexist (that is, they exist together in ratios, depending on pressure and temperature).
The boiling point of water is at 1.00 atm.
The boiling temperature increases as the pressure increases.
A pressure cooker can cook food faster because the water in it can be a liquid at higher than normal temperatures.
The critical point is where the curve ends because the liquid phase doesn't exist at high temperatures.
You can see the critical point in Table 13.3.
Oxygen cannot be liquefied above the critical temperature.

The axes are not scaleable.

There are several exotic phases of ice in this graph.

The melting point is at 1.00 atm.

At a fixed temperature, you can change the phase from solid to liquid by increasing the pressure.
The melting temperature of ice can be seen from the phase diagram.
When a car is driven over snow, the increased pressure from the tires causes the water to refreeze and form an ice layer.

The substance can be gas or solid at low pressures.

There is no liquid phase for water.
It accounts for the large losses of snow pack that never make it into a river, the automatic defrosting of a freezer, and the freeze-drying process applied to many foods.
Carbon dioxide has a standard atmospheric pressure of 1 atm.

The triple point for water is 273.16 K, which is more accurate than the melting point of water at 1.00 atm.

Table 13.4 shows the triple point values of other substances.

At the boiling temperature, the liquid and gas phases are in equilibrium.

If a substance is in a closed container at the boiling point, the liquid is boiling and the gas is condensing at the same rate without net change in their relative amount.
At the same rate at which gas molecule stick to the liquid or form droplets, Molecules in the liquid escape as a gas.
If the temperature and pressure are increased, equilibrium can be maintained by the same increase of boiling and condensation rates.

There are two different boiling points inside a closed container.

The gas pressure is higher and the rate at which gas molecule enter the liquid is faster because there are more of them.
The gas and liquid are in equilibrium.

Water and steam are two examples of equilibrium between liquid and gas.

They should be in equilibrium because the temperature is the boiling point.
The air surrounding an open pot is mixed with gas.
If pure water and steam are in a closed container at 1.00 atm, they would coexist, but with air over the pot, there are fewer water molecules to condense.
An open glass of water at this temperature will evaporate, even though the temperature and pressure correspond to the liquid region.
Again, the gas around it is air and not pure water vapor, so that the reduced evaporation rate is greater than the condensation rate of water from dry air.
The liquid phase remains if the glass is sealed.

On a hot summer day, a cup of water with ice cubes stays at.

As long as ice remains in the liquid, the temperature stays at the freezing temperature.

Vapor pressure is created by faster Molecules that break away from the liquid or solid and enter the gas phase.

An increase in temperature increases the vapor pressure of a substance.

In a mixture of gases, the total pressure is the sum of partial pressures of the component gases, assuming ideal gas behavior and no chemical reactions between the components.

The law is based on the idea that each gas creates its own pressure by interacting with other gases.
It's consistent with the fact that pressures add.
Water evaporates and ice sublimates when their vapor pressures exceed the partial pressure of water vapor in the surrounding mixture of gases.
Liquid droplets or ice crystals form if the vapor pressures are less than the partial pressure of water in the surrounding gas.

A phase change involves energy transfer.

We know that force is needed to separate atoms and molecules in liquids.
In a phase change from solid to liquid to gas, a force must be exerted to separate atoms.
Force exerted through a distance is work, and energy is needed to go from solid to liquid to gas.
The need for energy to melt ice or boil water is consistent with this.
The converse is also true.
Going from gas to liquid or liquid to solid involves atoms and molecule pushing together.

As they change between solid, liquid, and gas phases, watch as atoms and molecules are heat, cool, and compressed.

When the air temperature drops to or below the dew point on a banana leaf, it forms.

The expression "it's not the heat, it's the humidity" makes sense.

Sweat from our skin and water from our breathing passages help keep us cool in hot weather.
We feel hotter at a given temperature when the humidity is high.
Low humidity can cause an increase in the risk of respiratory infections by drying out the mucus in the throat.

The relative humidity tells us how much water is in the air.

The amount of water in the air depends on the temperature.
If the water droplets are small enough to stay in suspension, the fog may be caused by the condensation of water droplets.
If you want to dry your hair, blowing hot air over it is more effective than cold air because of the increase in temperature.

The amount of water in the air depends on the pressure of water.

The vapor pressure is equal to the partial pressure of water in the container after equilibrium has been achieved.
Vapor pressure increases as temperature increases.
Table 13.5 shows the values of water vapor pressure.

The saturation values are the vapor density and partial pressure created.

They increase with temperature and are not dependent on air.

They rely on the pressure of water.

The relative humidity is related to the pressure of water in the air.

The partial pressure is equal to the vapor pressure at 100% humidity.
If the partial pressure is less than the vapor pressure, then the humidity is less than 100%.
condensation occurs if the partial pressure is greater than the vapor pressure.
In everyday language, people refer to the capacity of air to hold water vapor, but this is not actually what happens.
The air does not hold the water vapor.
The amount of water in air is determined by the pressure of water in the air.

The ideal gas law can be used to calculate the density of water vapor in order to create a partial pressure.

The saturation vapor density is given in the table.

The problem needs to be solved in two steps.

We can convert the number of moles to grams if we solve the equation.

We need to use the mass of water in the periodic table to do this.

The ideal gas law can be solved.

The density in moles is converted to grams.

The density is obtained by taking the pressure of the water and adding it to it.

A partial pressure of equal to the vapor pressure of water at that temperature is created by the density found.
The relative humidity is 100% if the partial pressure is equal to the vapor pressure.
There can be no more than 17.2 g of water vapor per at that temperature.
This example shows how water vapor behaves like an ideal gas, if the density in the table is correct.
The maximum amount of water that air can hold is listed in Table 13.5.

We can use this and the data in Table 13.5 to do a variety of interesting calculations, keeping in mind that relative humidity is based on the comparison of the partial pressure of water in air and ice.

The temperature is the point at which the air is dry.

Where is the saturation density will determine the relative humidity.

The table shows that the relative humidity will be 100%.
The concentration of water vapor in that temperature is called the dew point.

The value of the saturation vapor density is shown in Table 13.5.

The saturation vapor density is seen to be.

Dew point is important because air temperature cannot drop below in part (b), or in part (c), without water vapor leaving the air.

The transfer of heat prevents the temperature from dropping.
Farmers keep track of the dew point because freezing temperatures are a greater possibility when it is below.
It is unlikely that condensation will occur.
Vapor doesn't condense in liquid drops if the temperature drops.

The air temperature drops more quickly when there is no heat in the air.

Liquid droplets do not evaporate at high temperatures because there is no heat removed from the gas to the liquid phase.
The large range of temperature in arid regions is explained by this.

It can evaporate at this temperature and pressure.

The bubbles of air in a glass of water are caused by dissolved air and other impurities.
If a bubble starts out at the bottom of the container, it contains water vapor.
The pressure inside the bubble is fixed at 1.00 atm.
As the temperature rises, the amount of air in the bubble stays the same, but the water vapor increases, and the bubble expands to keep the pressure at 1.00 atm.
Since the partial pressure of water is equal to 1.00 atm, water enters the bubble continuously.
The bubble has air and total pressure of 1.00 atm, so it can't reach this pressure.
The larger the bubble, the stronger the force.

The bubble expands to keep its pressure down.

Freeze drying is a process in which substances, such as foods, are dried by placing them in a vacuum chamber and lowering the atmospheric pressure around them.

Decreased atmospheric pressure results in a lower partial pressure of water.

For example, the amount of water from food will be enhanced.
Those with the greatest velocities will be the most likely to break away from the food.
Those remaining have a lower average temperature and a lower average speed.
freeze drying is the process of freezing and drying food.

There are different types of molecule that form a solid, liquid, or gas.

If you want to watch the phase change, add or remove heat.
You can change the temperature or volume of the container to see a pressure-temperature diagram.
Understand the interaction potential of the molecule.

The temperature is the quantity that is measured.

The temperature is related to the average energy of the atoms in the system.

The temperature at which there is no is called absolute zero.

Thermal equilibrium occurs when two bodies are in the same temperature.

Thermal expansion is large for gases, and relatively of continuous random motion of atoms and molecule.

The ideal gas law is where the average force per unit area is, the length of the container is, the volume of gas in the container is, and the temperature is.

The area is changed due to thermal expansion.

The average temperature of gases is related to the average volume.

When expansion is constrained, thermal stress is created.

The ideal gas law relates the pressure and volume to the number of gas molecules and the temperature.

Most substances have three distinct phases: gas, liquid, and number of molecule, and is the Boltzmann and solid.

Two phases coexist at a set of pressures and temperatures.

A line on a diagram.

The ideal gas law can be written and solved in terms of a single point on a phase diagram.

The ideal gas law is generally valid at temperatures that existed alone.

The total pressure is the sum of the partial pressures of all of the gases present.

The relative humidity is the fraction of water in a gas.

Vapor pressure can be used to determine the saturation vapor density.

Find out how many people are on Earth.

If you want to calculate the mass of a mole of people, give an example of a physical property that varies with the person.

The mass of a mole is compared to the temperature.

The final equilibrium temperature amount of gas is what the constant-volume gas thermometer contains.

Consider the zeroth law.

A pressure cooker has water and steam in it because of the formation and growth of crystals as equilibrium at a pressure greater than atmospheric water freezes, anywhere from 10% to 30% of biological pressure.

When animal or plant material is frozen, how does this greater pressure increase cells?

The graph is not to scale, and would food cook any faster in such axes?

On a day when the temperature is 170 m, frost damage to most plants occurs.

In order to conserve energy, room temperatures are assumed to be in the winter and summer.

A light bulb may operate at 2900 K.

When Hong Kong is warm, does the temperature decrease when you buy a small piece of land?

The land title tells you how much the change in temperature will cost.

As ocean temperatures rise, the ideal gas law to melting ice caps and also due to the expansion of water.

The gauge pressure in your car tires is an idea of the size of the effect, calculate the change in at a temperature when you drive it onto a ferry boat to Alaska.

When the engine is hot, large balloons are used to lift scientific fluid.

The coefficients are approximate because most of them have operating temperatures greater.

The average atomic and molecular speeds are small.

The object's escape speed from Earth is 11 km/s.

The escape velocity from the Moon is smaller.

The cylinder is dropped and the valve leaks.

The cylinder is cooled to dry ice temperature so that the hydrogen molecule can be 2.016 g/mol, which is equal to the safe repair rate.

If the average gas in your fusion experiment doesn't change phase and there is no leakage of energy, you can reduce the pressure to 1.00 atm.

The number of moles is equal to 44.0 g/ under of pressure.

The hydrogen molecule is equal to 2.016 g/ of 3.75 cm.

The space between balls has an average velocity of 192 m/s.

There is a lot of gas near the Sun.

The temperature and volume of the two important isotopes of uranium are nearly the same.

The light bulbs are filled with gas.

The air is dry.

What is the pressure on the mountain?

On a day, the temperature is and the relative humidity is 90.0%.

The density of water on a hot dry pressure increases with depth.

The copper block's weight is supported by the water's vapor pressure.

Using the ideal gas law, calculate force in water and compare this fraction with the density of water vapor in that creates a partial fraction supported in water.

Human lungs have a temperature and a pressure.

When the engine is hot and the rod is cold, the relative humidity is 80%.

If the temperature is high.