Energy and reaction rates in technology

SCIENCE in ACTION

MICHAEL JOHN UGLO
WELCOME to our ninth lecture in the Science in Action series.
The more you know, the less you want. Alternatively, the less you know the more you want. If a public figure is not doing well in PNG, he or she persists thinking that there is no one who should be above him or her. It is an embarrassment for that particular person and his supporters because he knows less and thus he wants more from where ever he lands his or her hands on.
Only stupid people do that, don’t they?
Energy and reaction rates
Energy is the ability to do work. It is therefore that work is also seen as a form of energy. It is the energy that moves in the direction of the applied force that does work. Energy is therefore a quantity that is measured in joules and for the same reason, work is also measured in joules.
Energy comes in the form of heat, light, sound and work like mechanical work done on moving parts as well as potential energy.
Energy in a closed system changes between two forms and these are the kinetic and potential energy. In chemical reactions it is atomic and the molecular arrangement of particles that brings about those two changes. The energy availability can be both reversible and non-reversible. Energy can be reversed or are irreversible because they degraded from those particle arrangements known as entropy.
Energy is therefore never created or destroyed form the beginning in that closed system. It is only converted from one form to the other. It is even dated back to the “big bang” initial stage when all of that energy is conserved from the hydrogen atoms and hydrogen molecules whether it be the nuclear reactions by the stars like our sun or the radioactive decay from the heavier elements like the uranium or thorium. It is therefore given in the law called the law of conservation of energy.
If there is an increase in energy, then there will be proportionally an increase in the mass of an object. The reason is, more particles will move in the direction of the applied force also known as displacement so the mass will hence increase.
Therefore, the law of conservation of energy also is the same as the law of conservation of mass. For instance, in a chemical reaction, the amount and number of particles or species of particles found in the reactants will be equal to the number of particles found in the products. This gives the explanation that all chemical reactions as identified in a chemical equation have to be balanced.
In chemical reactions there is an energy barrier that the reactants will have to overcome throughout its degree of freedom in order to cause a chemical reaction to take place to form new products. That amount of energy required is called the activation energy. That is the minimum energy needed for the reactant particles to gain enough energy to free themselves from their bonds hence break their bonds to react with the other reactant particle to form new products.
That is, the reactant particles gain enough energy to collide with each other to form new products. The successful collisions to form the new products happens at point called the threshold energy. The more successful collisions the more products are formed.
Temperature
Temperature is a determining factor that allows for those collisions. Increase in temperature means the particles gain increased strength to move more so more reaction takes place, or vice-versa, when temperature decreases, the rate of chemical reaction decreases. This energy is not lost but is held within the bond of the product and the enclosed system leading to an increased entropy. That is, heat, light, sound or electromagnetic radiation can be emitted but this is conserved in the closed system.
Virtual momentum or energy is experienced in chemical reactions whereby an unseen force of energy exerts impact on the particles to cause collision of particles and therefore chemical reactions. This results in the types of chemical reactions known as exothermic or exergonic and endothermic chemical reactions.
Chemical reactions that require a little start up energy proceed within themselves (spontaneously) without requiring any form of energy such as heat are called exothermic or exergonic chemical reactions. They release greater amounts of energy to the system or the environment resulting in a degraded form of energy.
For instance, if you light a piece of a magnesium strip, it gives a very brightly coloured flame. After the flame it leaves an ash called the magnesium oxide. The resulting energy or enthalpy is negative. Thus, it adds to creating a higher entropy. Whereas, in the endothermic chemical reaction it occurs without (non-spontaneous).
The particles are arranged in the order that it allows for the build-up or storage of chemical energy, hence lowering the entropy. For instance, in photosynthesis, sunlight is absorbed by the chlorophyll to combine with carbon dioxide and water to form glucose in the production of different types of sugars and cellulose with starch. This results in the net gain of energy resulting in a positive enthalpy.
Rates of chemical reaction can be increased with temperature. Temperature is a measure of the average kinetic energy of the particles of a substance such as a reactant. If that (temperature) is increased then, the particle collision will therefore, be increased resulting in an increase in the rate of the chemical reaction.
Also, pressure plays an important part in the chemical reaction rates especially for reactants at the solid-liquid phase of the mole fraction. A condition called the activation state complex in which the state of the pressure change is determined as to increase or decrease in the rate of the chemical reaction and that is considered in the molar concentration.
My Prayer for PNG today is: “Walk with me as one in Christ’s love. May our heart all beat as one, May we give ourselves completely, All I own and all I do, I give to you…”
Next week: Carbon compounds and chemical industries.

• Michael John Uglo is a science textbook author and a lecturer in avionics, auto-piloting and aircraft engineering. Please send comments to: [email protected]