Can someone explain kinetics to me?

Answer 1

In physical chemistry, chemical kinetics or reaction kinetics study reaction rates in a chemical reaction. Analysing the influence of different reaction conditions on the reaction rate gives information about the reaction mechanism and the transition state of a chemical reaction. In 1864, Peter Waage pioneered the development of chemical kinetics by formulating the law of mass action, which states that the speed of a chemical reaction is proportional to the quantity of the reacting substances.

Kinetics deal with the experimental determination of reaction rates from which a rate law and reaction rate constant are derived. Essential rate laws exist for zero order reactions (for which reaction rates are independent of initial concentration), first order reactions, and second order reactions, and can be derived for others through calculus. In consecutive reactions the rate-determining step often determines the kinetics. In consecutive first order reactions, a steady state approximation can simplify the rate law. The activation energy for a reaction is experimentally determined through the Arrhenius equation and the Eyring equation. The main factors that influence the reaction rate include: the physical state of the reactants, the concentrations of the reactants, the temperature at which the reaction occurs, and whether or not any catalysts are present in the reaction.


[edit] Factors that influence the rate of a reaction

Fig 1.1 - Collisions
Top - Collisions before increased concentration.
Bottom - Increased collisions after the concentration is increased.
[edit] Physical State
The physical state (solid, liquid or gas) of a reactant is also an important factor of the rate of change. When reactants are in the same phase, as in aqueous solution, thermal motion brings them into contact. However, when they are in different phases, the reaction is limited to the interface between the reactants. Reaction can only occur at their area of contact, in the case of a liquid and a gas, at the surface of the liquid. Vigorous shaking and stirring may be needed to bring the reaction to completion. This means that the more finely divided a solid or liquid reactant, the greater its surface area per unit volume, and the more contact it makes with the other reactant, thus the faster the reaction. To make an analogy, for example when you start a fire, first you put wood chips and small branches, you don't start with big logs right away. In organic chemistry On water reactions are the exception to the rule that homogeneous reactions take place faster than heterogeneous reactions.


[edit] Concentration
Concentration plays a very important role in reactions. According to the collision theory of chemical reactions, this is due to the fact that molecules must collide in order to react together. As the concentration of the reactants increases, the frequency of the molecules colliding increases, striking each other faster by being in closer contact at any given point in time. Imagine two reactants being in a closed container. All the molecules contained within are colliding constantly. By increasing the amount of one or more of the reactants you cause these collisions to happen more often, increasing the reaction rate (Figure 1.1).


[edit] Temperature
Temperature usually has a major effect on the speed of a reaction. Molecule at a higher temperature have more thermal energy. When reactants (reactant + reactant → product) in a chemical reaction are heated, the more energetic atoms or molecules have a greater probabilty to collide with one another. Thus, more collisions occur at a higher temperature, making a product in a chemical reaction. More importantly however, is the fact that at higher temperatures molecules have more vibrational energy, that is, atoms are vibrating much more violently, so raising the temperature not only increases the number of collisions but also collisions that can result in rearrangement of atoms within the reactant molecules. For example, a refrigerator slows down the speed of the rate of reaction since it cools the molecules. On the other hand, an oven gives heat (energy) to the molecules which in turn speeds up the rate of reaction, cooking the food faster.

Chemical kinetics can also be determined using a Temperature Jump. This involves using a sharp rise in temperature and observing the relaxation rate of an equilibrium process.


[edit] Catalysts
A catalyst is a substance that accelerates the rate of a chemical reaction but remains unchanged afterwards. The catalyst increases rate reaction by providing a different reaction mechanism to occur with a lower activation energy. In autocatalysis a reaction product is itself a catalyst for that reaction possibly leading to a chain reaction. Proteins that act as catalysts in biochemical reactions are called enzymes. Michaelis-Menten kinetics describe the rate of enzyme mediated reactions.

In certain organic molecules specific substituents can have an influence on reaction rate in neighbouring group participation.

Agitating or mixing a solution will also accelerate the rate of a chemical reaction, as this gives the particles greater kinetic energy, increasing the number of collisions between reactants and therefore the possibility of successful collisions.

Increasing the pressure in a gaseous reaction will increase the number of collisions between reactants, increasing the rate of reaction.


[edit] Equilibria
While chemical kinetics determines the rate of the chemical reaction, chemical equilibrium determines the extent to which the reaction will occur. In a reversible reaction, chemical equilibrium is reached when the reaction rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations of the reactants and products no longer change. This is demonstrated in the classical example of the Haber-Bosch process. Le Chatelier's principle can then be used to predict the effect of change in concentration, temperature or pressure on the position of that chemical equilibrium. Chemical clock reactions such as the Belousov-Zhabotinsky reaction demonstrate in a spectacular way that component concentrations can oscillate for a long time before finally reaching equilibrium.


[edit] Free energy
In general terms, the free energy of a reaction determines if a chemical reaction will take place, the kinetics will then tell how fast the reaction is. A reaction can be very exothermic but will not happen in practice if the reaction is too slow. If a reactant can react to form two different products, the thermodynamically most stable product will generally form except in special circumstances when the reaction is said to be under kinetic reaction control. The Curtin-Hammett principle applies when determining the product ratio for two reactants interconverting rapidly each going to a different product. It is possible to make predictions about reaction rate constants for a reaction from Free-energy relationships.

The kinetic isotope effect is a difference in the rate of a chemical reaction when an atom in one of the reactants is replaced by one of its isotopes.

Chemical kinetics provide information on residence time and heat transfer in a chemical reactor in chemical engineering and the molar mass distribution in polymer chemistry.

Answer 2

Kinetics means movement. I assume you are wondering about the energy of kinetics. A moving object has a certain amount of energy based on the mass of the object combined with the speed the object is traveling. The amount of enrgy is caled kinetic energy and is realeased when the object collides with another object. The same can be said for a box sitting precariously on a high shelf. The box has stored or potential kinetic energy in it because it has the potential to fall, when it does fall, it has kinetic energy that increase at the rate of the mass times the acceleration of gravity. It's early, I could probably explain better after a couple coffees.

Answer 3

There's more than one definition just use the link to find the info you want :o)

Kinetics
From Wikipedia, the free encyclopedia
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Kinetics, derived from the Greek word κίνησις (kinesis) meaning "movement", may refer to:


[edit] Science
Chemical kinetics, the study of chemical reaction rates.
In physics, kinetics is another name for dynamics, not to be confused with kinematics.
In biochemistry, enzyme kinetics and receptor-ligand kinetics.

[edit] Arts
Kinetic art

[edit] Business
Kinetics, a technology company.

Answer 4

In physical chemistry, chemical kinetics or reaction kinetics study reaction rates in a chemical reaction. Analysing the influence of different reaction conditions on the reaction rate gives information about the reaction mechanism and the transition state of a chemical reaction. In 1864, Peter Waage pioneered the development of chemical kinetics by formulating the law of mass action, which states that the speed of a chemical reaction is proportional to the quantity of the reacting substances.

Answer 5

Enzyme Kinetics is the technology that study the dynamics (interactions) of chemical reactions that are catalyzed (inspired) through enzymes. In different words, whenever you take advantage of and enzyme to assist a chemical reaction ensue, the ensuing pastime and how the chemical substances artwork jointly is recognize because the enzyme kinetics. Does that make experience? Take care! Jim

Answer 6

Kinetics is a movement.

Answer 7

the branch of mechanics concerned with the forces that cause motions of bodies

Answer 8

It is energy from movement!