Sublimation-Solid to Gas Phase Transformation, Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

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What is Sublimation?

  • The term sublimation is the passage or the transformation or conversion that substances undergo when passing from one state to another, a solid substance to gas.
  • Sublimation as the transition of a substance from the solid phase to the gaseous phase without changing into the liquid phase. This process is an endothermic phase transition that occurs at a temperature and pressure below the triple point of the substance. Desublimation or deposition is the reverse of this process in which a gas is directly converted into solid-state.

Sublimation-Solid to Gas Phase Transformation

  • Elements and compounds mainly possess three different states at various temperatures.
  • The transition from solid state to gaseous state requires a transition of solid-state to liquid state and liquid state to a gaseous state.
  • If solids possess sufficient vapour pressure at a particular temperature, then they can directly sublime into the air.
  • Solids which have high pressure at their triple point show sublimation.
  • The triple point is the point at which the pressure and temperature of the substance are such that it can exist in all three states of matter simultaneously. The triple point is a characteristic point of a substance.
  • There are various examples of sublimation which are experienced by us in our everyday life.

Examples of Sublimation

  • The best example of sublimation is dry ice which is a frozen form of carbon dioxide. When dry ice gets exposed to air, dry ice directly changes its phase from solid-state to gaseous state which is visible as fog. Frozen carbon dioxide in its gaseous state is more stable than in its solid-state.
  • Another well-known example of sublimation is naphthalene which is an organic compound. Naphthalene is usually found in pesticides such as mothball. This organic compound sublimes due to the presence of non-polar molecules that are held by Van Der Waals intermolecular forces. At a temperature of 176 F naphthalene sublimes to form vapours. It desublimates at cool surfaces to form needle-like crystals.
  • Sublimation finds practical application in forensic sciences. Dye-sublimation printers help in rendering digital pictures in a detailed and realistic fashion which helps in the analysis of substances. Chemists usually prefer sublimation as a purification method to purify volatile compounds.

Phase Transition: Solid to Gas

  • Sublimation is the process of transformation directly from the solid phase to the gaseous phase, without passing through an intermediate liquid phase. It is an endothermic phase transition that occurs at temperatures and pressures below a substance՚s triple point (the temperature and pressure at which all three phases coexist) in its phase diagram.
  • At a given temperature, most chemical compounds and elements can possess one of the three different states of matter at different pressures. In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state. But at temperatures below that of the triple point, a decrease in pressure will result in a phase transition directly from the solid to the gaseous. Also, at pressures below the triple point pressure, an increase in temperature will result in a solid being converted to gas without passing through the liquid region.
Phase Transition: Solid to Gas
  • Phase Diagram of a Pure Substance Notice the triple point of the substance. At temperatures and pressures below those of the triple point, a phase change between the solid and gas phases can take place.
  • For some substances, such as carbon and arsenic, sublimation is much easier than evaporation. This is because the pressure of their triple point is very high and it is difficult to obtain them as liquids. The solid has such high vapor pressures that heating leads to a substantial amount of direct vaporization even before the melting point is reached.
  • The process of sublimation requires additional energy and is therefore an endothermic change. The enthalpy of sublimation (also called heat of sublimation) can be calculated as the sum of the enthalpy of fusion and the enthalpy of vaporization.
  • The reverse process of sublimation is deposition (i.e.. , gas to solid) . For example, solid iodine, , is easily sublimed at temperatures around Even ice has a measurable vapor pressure near its freezing point, as evidenced by the tendency of snow to evaporate in cold dry weather.
  • There are other solids whose vapor pressure overtakes that of the liquid before melting can occur. Such substances sublime; a common example is solid carbon dioxide (dry ice) at 1 atm of atmospheric pressure.

Questions

What is the Sublimation Process?

Answer:

  • Sublimation, including melting, freezing, and evaporation, is a form of phase transition, or shift in a state of matter.
  • A substance transforms from a solid to a gas by sublimation without ever going through a liquid phase. A common example of sublimation is the dry ice, heavy

How is Sublimation Used in Everyday Life?

Answer:

The bathroom air fresheners used. The strong sublimes and releases over a certain period of time the good smell in the bathroom. Naphthalene mothballs are used to scare moths and other pest՚s home.

What Things Can Sublimate?

Answer:

A range of solids, including water, iodine, arsenic, and solid carbon dioxide (dry ice) , can sublimate at normal temperatures and pressures. Other materials can sometimes be made to sublimate by creating conditions of low pressure.

What is the Sublimation Method of Separation?

Answer:

A mixture of solids is isolated by sublimation, one of which is sublime. Many liquids change immediately, without going through the liquid state, from solid to vapor on heating. This process is referred to as sublimation.

Does Sublimation Require Heat?

Answer:

The sublimation molar heat is the amount of energy that must be applied to a solid mole at constant pressure to convert it directly into a gas.

What is Sublimation Solid to Gas?

Answer:

  • Sublimation is the conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage.
  • For those of us interested in the water cycle, sublimation is most often used to describe the process of snow and ice changing into water vapor in the air without first melting into water.

Is the Sublimation of the Solid to a Gas a Physical Change?

Answer:

Sublimation is a physical change. When a substance sublimes, it changes from a solid to a gas without going through the liquid phase.

What Are Three Examples of Physical Changes?

Answer:

  • Examples of physical change include changes in the size or shape of matter. Changes of state for example, from solid to liquid or from liquid to gas are also physical changes.
  • Some of the processes that cause physical changes include cutting, bending, dissolving, freezing, boiling, and melting.

What is a Gas to a Solid Called?

Answer:

  • Deposition is the phase transition in which gas transforms into solid without passing through the liquid phase. Deposition is a thermodynamic process.
  • The reverse of deposition is sublimation and hence sometimes deposition is called Desublimation.

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