what is the process that changes a substance from a liquid to a gas below the boiling point

You might have observed how an ice cube melts at room temperature to become water or how h2o boils to eventually transform into vapor and evaporate. These changes in affair are known as changes of state. But why does affair does then? The affair might change states when it absorbs or releases energy. These changes do not involve any change or alteration in the chemical properties of the substance involved. In this commodity, we will have a expect at the alter of state of affair, the reason behind it, and the diverse processes involved.

Change of State

Matter unremarkably exists in three states which are solids, liquids, and gases. The modify of the substance from i state to some other is termed a change of state. Two common changes of country accommodate the alter from solid to liquid and from the liquid country to vapor/gas and vice versa.

When a substance absorbs a certain corporeality of free energy, its atoms and molecules move in a rapid fashion due to which its kinetic energy increases. This increase in kinetic energy helps in pushing the particles farther apart from each other, hence the substance changes grade. The free energy of the substance in this state is known equally thermal energy or heat.

Heat and Change of State of Matter

The Alter of State from Solid to Liquid

The alter of state of a substance from solid to liquid is known as melting. Until all of the solid substance melts, the temperature of the system remains constant. Hence, both the solid and liquid states of matter exist with each other in thermal equilibrium during the transition state. Hither, the temperature at which both these states coexist is known as its melting point. Melting Point is a special property of the substance which also depends on the pressure. At standard atmospheric pressure, the melting point of a substance is known equally its normal melting point.

The process of melting and freezing of water

The modify of land from liquid to solids is known as freezing and the bespeak at which the liquid and solid country exist in thermal equilibrium is known as the freezing point. When the pressure effectually a substance is increased, the freezing signal also increases. It's easier to keep solid substances under bang-up force per unit area. As the molecules of solids are closely packed together, they are denser than liquids. Through freezing, the molecules of the substance are compacted further in a much smaller space

For instance ,

Over a slab of ice, if we put a metallic wire with two blocks of equal weight fastened at both ends, we will discover that the metallic wire passes through the ice slab. This upshot is because due to an increase in pressure, the ice below the wire melts at lower temperatures.

A metallic wire with equal weights tied on both of its ends placed on top of an ice slab

When the wire passes through the slab, the water freezes to render ice again. This phenomenon of the metallic wire passing through the ice slab without splitting it in two parts is known as regelation. This makes skating on snow possible equally the snowfall below skates due to high pressure level transforms into h2o and therefore acts as a lubricant

A alter of country from liquid to solid is known as fusion. For instance, liquid nitrogen (N2) is turned into a solid by putting it in a sealed chamber with high pressure.

The Modify of State from Liquid to Vapour

If the heat is all the same supplied once all of the water ice is converted to h2o, we will find a rising in temperature till 1000C of temperature is reached. Subsequently that, the estrus that is supplied to water is used in the transition of h2o into a vapor state. Hence, the change of state from liquid to gaseous/vapor country is known as vaporization.

At boiling point, water transforms from a liquid to a vapor state through the process of evaporation

Hither also, until all the liquid is converted to a vapor state, the temperature of the system remains constant. Hence, the temperature at which both the gaseous and liquid land of the substance coexist in thermal equilibrium is known equally the boiling point of the substance.

The process of condensation and evaporation

At standard pressure, the boiling indicate of a substance is known as its normal boiling point. With increasing pressure, the boiling point of a substance too increases and more heat will be required to convert the liquid into a vapor state. Similarly, every bit the pressure level decreases, the boiling point of a substance is too reduced.

This is why, cooking is a fleck difficult in hilly areas every bit the atmospheric pressure level is lower on high altitudes, which lowers the boiling point of water. Therefore, a pressure level cooker is used to increase the boiling point, thereby making the procedure of cooking fast.

Triple Betoken: The pressure and temperature at which the iii curves, the vaporization curve, the fusion curve, and the sublimation curve meets so that all the iii phases of a substance exist together is known as the triple betoken of the substance. For example, the triple point of water exists at a temperature of 273.sixteen K and a pressure of 6.eleven ten 10–three Pa.

Triple Point of Water

Phases of Matter

Phases refer to the course of matter. Solid, liquid, and gas (vapor) are the iii fundamental phases of thing, however other phases such as crystalline, colloid, glassy, amorphous, and plasma also exist. A stage modify occurs when a affair of phase in one form transforms into a different form.

Phases of Thing

Not all substances laissez passer through the three states sequentially: solid, liquid, gas. For case, dry ice directly goes from a solid to a gaseous state through the process of sublimation. Here both solid and gaseous states coexist.

There are various processes involved in the phase alter of matter known as deposition, condensation, vaporization, humid, melting, solidification, and sublimation. A graph plotted between the Temperature and Pressure of a substance is known as a P-T diagram or a phase diagram.

Applications of Change of State

• The frost on the leaves on a winter morning is a result of the water vapor in the air transitioning into a solid when information technology comes in contact with the leaves.
• Melting of an Ice Cube.
• Steam rising on boiling of water.
• A glass of ice water when put at room temperature forms water aerosol on the outer side of the drinking glass equally the vapor condenses into water.

Things to Call back

• The matter might modify states when it absorbs or releases energy.
• These changes do non involve any modify or alteration in the chemical properties of the substance involved.
• The alter of state of a substance from solid to liquid is known as melting.
• The temperature at which both these states coexist is known every bit its melting point.
• The change of state from liquid to gaseous/vapor state is known as vaporization.
• Cooking is difficult in hilly areas as the atmospheric pressure level is lower on high altitudes, which lowers the humid indicate of water.
• When the force per unit area around a substance is increased, the freezing indicate too increases.
• Sublimation is the process of change of land of a substance from solid to vapor directly without going through the liquid land too.
• Phases refer to the form of matter.
• Solid, liquid, and gas (vapor) are the three fundamental phases of matter, however other phases such every bit crystalline, colloid, glassy, amorphous, and plasma also be.

Sample Questions

Ques. What refers to a modify of country? (1 mark)

Ans. Thing usually exists in iii states which are solids, liquids, and gases. The change of the substance from ane state to another is termed a change of state.

Ques. What is the reason behind water boiling at low temperatures at High elevations? (two marks)

Ans. Water boils at depression temperatures at high elevations as the atmospheric pressure level is lower at higher altitudes. This leads to difficulty in cooking at college altitudes. Therefore, a pressure level cooker is used for cooking in hilly areas as it increases the pressure, which farther increases the boiling point of h2o and makes cooking easier.

Ques. What is condensation? What will happen to the temperature of the air surrounding the glass when condensation forms on a drinking glass of ice water? (1 marking)

Ans. Condensation is the transition from the gaseous to the liquid state of materials. It'south the polar opposite of vaporization. Atoms and molecules course clusters during condensation. The clusters eventually grow large enough to produce droplets. When water vapor (in its gaseous grade) in the air comes into contact with a colder surface, condensation happens. For instance, a steamy mirror, forenoon dew in the sky, fog in the air

When condensation occurs on a glass of ice h2o, the temperature of the air surrounding the drinking glass increases.

Ques. Explicate the change of state that takes place in the process of melting. (two marks)

Ans. Melting refers to the process of change of a substance from a solid into a liquid state. When heat is supplied to a solid, the motion of its molecules speeds up which in turn helps them overcome their forcefulness of attraction and so that the molecules transform into a liquid.

Ques. What are the 3 states of matter? (3 marks)

Ans. The 3 states of matter are solid, liquid and gases. They tin be further understood as:

• Solid: A solid is a state of matter in which particles are grouped in such a way that their shape and volume remain relatively steady. The atoms or molecules of a solid are securely bonded via chemic bonds, which gives information technology a rigid course.
• Liquid: A fluid with the consistency of h2o or oil that flows freely but has a consequent volume.
• Gas: A state (such as air) that does not take its ain shape or volume but expands indefinitely.

Ques. Explain the process of vaporization. Give examples of the same. (3 marks)

Ans. The process of vaporization occurs when a liquid transforms into a gas. When you lot boil water, you can detect the vaporization procedure. Evaporation and boiling are the ii methods of vaporization. The rapid vaporization of a liquid is known as boiling, and the steam that comes out of a boiling kettle is actually visible water vapor. With the assist of vaporization, the table salt is extracted from seawater.

Ques. If five J is the latent heat of ice melting, what is the heat of transition from 0 ^o C ice to 15 ^o C water, if 12 J is the estrus of transition from 0 ^o C water to 15 ^o C water? (2 marks)

Ans. Heat of transition from 0^oC ice to 15^oC water= 12 + five = 17 J.

Ques. What mainly determines or leads to a modify of state in a substance? (2 marks)

Ans. The alter of land in a substance is mainly due to either:

• Temperature
• Pressure

Ques. How does a solid transform into a liquid? (ii marks)

Ans. The kinetic energy of the molecules of a solid substance increases every bit more than and more oestrus is supplied to it, as a upshot of which these particles begin vibrating. As the particles vibrate with a higher frequency, they overcome the forces of attraction betwixt them, getting detached from their original position. Hence, they are able to move more freely and transforms into a liquid state through the process of melting.

Ques. How does a liquid transition into a gas? (2 marks)

Ans. The molecules of a liquid move with a greater speed every bit more heat is supplied to information technology. Once it reaches a certain temperature, the particles gain enough free energy to intermission away all the bonds or force of attraction between the liquid molecules. They undergo a phase change and transform into vapors through the process of evaporation.

Ques. What is sublimation? Give an case. (2 marks)

Ans. The process of a substance in a solid state to transform directly into vapor grade without transitioning through the liquid country is known as sublimation.

For eg, dry out ice changes straight from solid to vapor phase.

Ques. If the heat of transition from 0 ^o C water ice to 15 ^o C water is 10 J, what is the heat of transition from 0 ^o C water ice to xv ^o C water? (2 marks)

Ans. Rut of transition = 10+15

= 25 J

Hence, the heat of transition required to transform 0^oC water ice to 15^oC of water is 25 J.

Ques. What is deposition? (3 marks)

Ans. The deposition is a phase transition in which a gas becomes a solid without starting time passing through the liquid phase. When molecules settle out of a solution, this is called degradation.

Frost is the almost common example of degradation. The deposition of water vapor on a solid surface acquired by boiling air or air containing h2o vapor is known equally frost. When a surface, such equally a leafage, is at a temperature below the freezing point of water and the surrounding air is humid, solid frost forms. Water vapor, for example, transforms immediately to ice in sub-freezing air without first becoming a liquid.

Ques. Why water in solid form is less dumbo than liquid water? (3 marks)

Ans. When water is frozen, the orientation of its hydrogen bonding is such that the molecules are pushed farther apart than in the case of liquid water and hence they take up more than space. Hydrogen bonding is responsible for making water ice less dense than liquid water.

Ques. Why the energy of sublimation of solid helium is lower than the energy of ice? (three marks)

Ans. The atoms in solid helium are held past weaker Van der Waals forces. Hence, the energy required for sublimation is less while in the example of ice, its molecules have strong hydrogen bonds between them. For this reason, ice needs higher energy and higher temperatures to undergo the process of melting. Hence, ice has higher energy of sublimation than solid Helium.

Ques. Proper name the processes involved in the change of land. (5 marks)

Ans. The various processes involved are:

• Solidification, oft known as freezing, is a phase shift in the liquid affair that produces a solid.
• A solid melts into a liquid when heated through the process of melting. This process occurs at a precise temperature known equally the melting point.
• Condensation is the transition from the gaseous to the liquid country of materials.
• The process of vaporization occurs when a liquid transforms into a gas.
• Sublimation is the procedure of converting a solid to a gas without going through the liquid phase.
• The deposition is a phase transition in which a gas becomes a solid without beginning passing through the liquid stage.
• When a liquid is heated to its boiling point, it undergoes rapid evaporation.

edwardsponswed68.blogspot.com

Source: https://collegedunia.com/exams/change-of-state-melting-point-boiling-point-applications-physics-articleid-1348

Share this post