What does phase transformation involve?
A phase transformation occurs when one material changes its composition or structure. The transformation can be caused by a change in temperature so that no other material is involved or it may involve the reaction with another material, which may or may not be a ceramic, and may be in the liquid or gaseous phase.
What is the phenomenon involved in phase transformation?
What is/are the phenomenon involved in phase transformation? new phase is nucleation and increase in size of the nucleus at the expense of the parent phase is growth. Explanation: Two types of nucleation – Heterogeneous and Homogeneous whereas fusion and fission are nuclear reactions.
Which type of phase transformation is Diffusionless phase transformation?
Diffusionless transformations, also called displacive transformations, are solid state transformations that do not require diffusion, i.e. long range movements of atoms, for a change in the crystal structure to occur.
What is the major driving force for any phase transformation?
From classical nucleation theory this transformation is known to be driven by changes in bulk free energy content; the higher the driving force the faster the transformation.
What are the driving forces that indicate a chemical reaction?
When both cases are satisfied, i.e. if the change in enthalpy is negative and the change in entropy is positive, the reaction is said to be spontaneous, and thus, enthalpy and entropy are the two driving thermodynamic forces of chemical reactions./span>
What is meant by driving force of chemical reaction?
The driving force behind a chemical reaction can probably be seen in terms of the difference between the energetic states of its reactants and products. Relating the driving force to the reaction rate (“flux”) was achieved by combining the concentration dependencies of both the force and the rate.
Is enthalpy or entropy the driving force?
Enthalpy is NOT the force driving the reaction forward. Therefore, if the reaction is spontaneous (as it must be if you can see bubbles of gas forming), the drive towards maximising entropy must be driving the reaction forward.
What is the driving force of a double replacement reaction?
The driving force behind double-replacement reactions is the formation of a stable product. Double replacement reactions have the form. Ions in compounds AB and CD switch partners.
What is the nature of this driving force?
Leonardo da Vinci described water as “the driving force of nature.” There are many ways in which water can be used as a force, or merely witnessed as a force of nature. Thoreau refers to the process of erosion./span>
What is an equilibrium state?
Equilibrium, in physics, the condition of a system when neither its state of motion nor its internal energy state tends to change with time. For a single particle, equilibrium arises if the vector sum of all forces acting upon the particle is zero.
What is the driving force for steady state diffusion?
concentration gradient
What other force drives diffusion?
The driving force for diffusion is the thermal motion of molecules. At temperatures above absolute zero, molecules are never at rest. Their kinetic energy means that they are always in motion, and when molecules collide with each other frequently, the direction of the motion becomes randomized./span>
What 4 things affect the rate of diffusion?
Several factors affect the rate of diffusion of a solute including the mass of the solute, the temperature of the environment, the solvent density, and the distance traveled./span>
How does size affect rate of diffusion?
When the cell increases in size, the volume increases faster than the surface area, because volume is cubed where surface area is squared. When there is more volume and less surface area, diffusion takes longer and is less effective. this is actually why cells divide./span>
How is diffusion affected by surface area?
When a cell’s surface area increases, the amount of substances diffusing into the cell increases. This is known as the surface area/volume ratio (SA/V ratio). A cell will eventually become so large there is not enough surface area to allow the diffusion of sufficient substances like oxygen and it will die.
How long does diffusion last?
Diffusion can occur through a membrane or not and doesn’t require any energy. How long does diffusion last? Until it reaches equilibrium, when there is an equal amount of the substance distributed everywhere.
What substances can move into or out of cells by diffusion?
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.
Does diffusion stop when equilibrium is reached?
It is the random motion of the molecules that causes them to move from an area of high concentration to an area with a lower concentration. Diffusion will continue until the concentration gradient has been eliminated. At equilibrium, movement of molecules does not stop./span>
What is the main cause of diffusion?
The primary cause of diffusion is random motion of atoms and molecules in a substance.
What happens to molecular diffusion when equilibrium is reached?
Even when equilibrium is reached, particles of a solution will continue to move across the membrane in both directions. However, because almost equal numbers of particles move in each direction, there is no further change in concentration./span>
Can dynamic equilibrium ever be reached?
While reactions at dynamic equilibrium are reversible (can proceed in either direction), those at static equilibrium are irreversible and can only proceed in one direction./span>
How do you recognize the attainment of equilibrium?
At equilibrium: the forward and backward reactions are still happening. the forward and backward reactions have the same rate of reaction….Rate of attainment of equilibrium
- the pressure of a reacting gas.
- the concentration of a reacting solution.
- the temperature of the reaction mixture.
- the presence of a catalyst.
What happens to the forward and reverse rates at equilibrium?
All reactions tend towards a state of chemical equilibrium, the point at which both the forward process and the reverse process are taking place at the same rate. Since the forward and reverse rates are equal, the concentrations of the reactants and products are constant at equilibrium.
How many equilibrium positions are there?
There are infinitely many different equilibrium positions that satisfy K. We could have [B]=20 M and [A]=0.1 M. Or we could have [B]=1 M and [A]=0.005 M. Those are two different equilibrium positions that are both at equilibrium.