Matter exists chiefly in four forms: solid, liquid, gas, and plasma. The conversion of matter from one state to another is called a phase change. This process occurs when a large amount of energy is gained or lost. Phase change also depends on factors like pressure and temperature.
Different Types of Phase Change
A phase is a form in which a substance exists.On earth, the different states of matter are solid, liquid, gas, and plasma. Each form of matter has unique properties including specific heats, melting points, and boiling points. Under certain conditions, different phases can coexist.
There are eight thermal processes through which matter can attain phase change. They are melting, freezing, evaporation, condensation, sublimation, deposition, ionization, and recombination. These eight phases exist under different temperatures and pressure conditions.
- Freezing:Change of a substance from liquid phase to solid
- Melting:Change from solid phase to liquid
- Vaporization:Change from liquid to gaseous form
- Condensation:Change from gas to liquid form
- Sublimation:Change from solid to a gas without becoming a liquid
- Deposition:Change from gas to solid without becoming a liquid
- Ionization:Change from a gas phase to plasma (ionized particles)
- Recombination:Change from plasma to gas
Relationship between Phase Change and Heat Transfer
When matter undergoes a phase change, heat is either absorbed or released. This process is calledheat transfer, and it can occur in three ways: conduction, convection, and radiation.
Latent heat transfer vs sensible heat transfer
Heat transfer comprises latent and sensible processes. Latent heat transfer is a phenomenon where the phase change occurs without any change in internal temperature. Whereas in sensible heat transfer, phase change does not occur but the internal temperature changes.
For example, consider sunlight warming a glass of water. The water absorbs the thermal energy but doesn’t change its phase. However, the water reaches a higher temperature as heat is added. This process demonstrates sensible heat transfer – one that you can sense through temperature measurement.
For an example of latent heat transfer, consider a glass filled with ice cubes. The ice cubes receive thermal energy from the same sunlight, and as a result, begin to change their phase from solid to liquid. The temperature of the ice will remain at 0°C (32°F) until all of the ice has melted. This phenomenon is called latent heat transfer.
Phase Change Materials as an Engineering Tool
Engineers harness the physical phenomenon of phase transition in applications that require storing or releasing thermal energy. Phase change materials (PCMs) act like a battery that can store thermal energy when melting or vaporizing. This stored energy can be released back when the material is cooled again. Engineers use PCMs for the thermal control of buildings, photovoltaic plants, hot and cold water storage systems, and thermal management of electronic components.
Paraffin wax is one of the commonly used PCMs.Other categories of PCMs include hydrated salts, non-paraffin organics, and metallic phase change materials.
FAQs
The conversion of matter from one state to another is called a phase change. This process occurs when a large amount of energy is gained or lost. Phase change also depends on factors like pressure and temperature.
What is the explanation of phase change? ›
Phase change occurs when energy and pressure are added or removed from a system The phases most often found in nature are solid, liquid, and gas/vapor. Evaporation is the process of changing from a liquid to a vapor, also called boiling. This happens at the boiling point of a liquid.
What is the phase change material for thermal management? ›
Phase Change Materials (PCMs) are ideal products for thermal management solutions. This is because they store and release thermal energy during the process of melting & freezing (changing from one phase to another).
What is happening to thermal energy during a phase change? ›
Since the energy involved in a phase changes is used to break bonds, there is no increase in the kinetic energies of the particles, and therefore no rise in temperature. Similarly, energy is needed to vaporize a liquid to overcome the attractive forces between particles in the liquid.
What are the phase changes of heating? ›
Heat going into a substance changes it from a solid to a liquid or a liquid to a gas. Removing heat from a substance changes a gas to a liquid or a liquid to a solid. Two key points are worth emphasizing. First, at a substance's melting point or boiling point, two phases can exist simultaneously.
What describes a phase change? ›
A phase change is when matter changes to from one state (solid, liquid, gas, plasma) to another. (see figure 1). These changes occur when sufficient energy is supplied to the system (or a sufficient amount is lost), and also occur when the pressure on the system is changed.
What is a phase change quizlet? ›
phase change. reversible physical change that occurs when a substance changes from of matter to another. sublimation. solid to gas-endothermic. deposition.
What is a phase change in thermal physics? ›
The conversion of matter from one state to another is called a phase change. This process occurs when a large amount of energy is gained or lost. Phase change also depends on factors like pressure and temperature.
What is the thermal phase change model? ›
The thermal phase change model uses scaling factors (Cl and Cv) to calculate the heat transfer from the interface to the liquid phase or gas phase. The default value is 1. The zero resistance is equivalent to an infinite phase specific heat transfer coefficient.
What are the thermal properties of phase change materials? ›
Key thermophysical properties of phase-change materials include: Melting point (Tm), Heat of fusion (ΔHfus), Specific heat (cp) (of solid and liquid phase), Density (ρ) (of solid and liquid phase) and thermal conductivity. Values such as volume change and volumetric heat capacity can be calculated there from.
Mass of the substance heated – as the mass of the substance increases, the number of particles in the substance increases. This means that there are a larger number of particles to heat, therefore making it more difficult to heat. Type of material – certain materials are easier to heat than others.
Where does energy go during phase change? ›
In order to move to a higher energy phase, energy must be absorbed from the surroundings (endothermic). In order to move to a lower energy phase, energy must be released to the surroundings (exothermic). Figure 13.4. 2: The energetics of phase transitions.
Why are phase changes important? ›
Phase changes are important for our lives because they help provide heat, cool our food, and regulate our weather, among other things.
What happens to temperature during a phase change? ›
During a phase change, the temperature remains the same until the phase change is complete. This is how you can tell if a phase change is occurring.
What heat is needed for phase change? ›
The energy required to change a substance of mass into a new phase is given by the equation Q = m L where is the latent heat of either vaporization (liquid to gas) or fusion (liquid to solid).
What three phase changes require heat energy to be added? ›
Hence, the three phase changes that require energy to perform are fusion, vaporization and sublimation. Note: The example of fusion is ice melting to form water; vaporization is water forming water vapors, while that of sublimation is iodine in solid converting to gas.
What is the explanation of the term phase? ›
Those portions of a system that are physically distinct and mechanically separable from other portions of the system are called phases. Phases within a system exist in a gaseous, liquid, or solid state. Solids are characterized by strong atomic bonding and high viscosity, resulting in a rigid shape.
What is phase difference explanation? ›
Phase difference can be defined as the difference between the position of the two waves propagating in the same direction (in a particular time), they don't rise or fall together. At a particular time, they make a difference in amplitude in their motion.
What are the 5 phase changes? ›
Define phase change. Define melting, freezing, vaporization, condensation, sublimation, and deposition.
