Batteries are a compact portable energy source, we use batteries in our life; it has played a very important role within our modern society such as to operate portables appliances. We use torches as a backup lighting system; we use batteries on our mobile phones, as well as batteries in our cars. Many of us, do not even have the realisation that it is a perfect example of application of chemistry in daily life.The battery industry has become a very profitable market.
The market is saturated and we see more and more brands, each and every one of them claiming that they yield better value and effectiveness. Rechargeable batteries, allow the recharging of the batteries that allows the battery to be used for more than once. They are now available in the market, but they do not come at a cheap price, you will need to invest on a charger, a device you need to acquire to charge up the rechargeable battery.The topic was chosen as this matter has left many of us dazzled, the need of battery is unquestioned but they come at relatively expensive price that vary across different brands.
So which one do we choose among the brands within the market? Is it justified to spend money on investing on a charger so we can use rechargeable batteries? Or is it better to keep using the traditional batteries? What kind of battery usage do we need until it is economical to get rechargeable batteries? This essay will help answer these questions.Theoretical Background:1.1 History of Battery:On 1660 Otto Von Guericke built the first static generator, which is a glass ball turned by hand which rubbed against cloth which create sparks of electricity. After Otto’s discovery, more scientists are involved and fascinated by electricity. But it is not until 20th of March 1800, came one of the greatest breakthroughs in the electricity experiments. A professional disagreement, over the results of an experiment, between Luigi Galvani and Alessandro Volta two leading scientists, led Volta to prove that when certain metals and chemicals come into contact with each other they can produce an electrical current.
He placed together several pairs of silver and zinc discs separated by paper soaked in salt water and an electrical current was produced, Volta had produced the first battery. These are called Voltaic battery, or usually referred in Chemistry as Galvanic Cells. Refer to Figure 3 (P.5) for illustration.1.2 What is a battery?So what exactly are batteries? This seems like an easy question, even someone as young as 5 year old will know it, as they are playing their game-boy or remote control they use batteries. Unfortunately there are more to it than just an apparatus that provide electricity, it is a complex matter that has been researched by scientists since ages ago.1 Batteries come in different varieties and sizes.
Some are small enough to fit in our watches, yet many are strong enough to power cars, and planes. Figure one shows the common household batteries we use on everyday life.”Energy cannot be created nor destroyed, energy can only be changed from one form into another.”2Law of Conservation Energy.In theory energy cannot be created or destroyed, it can only be changed from one form into another.
There are different forms of energy; electrical, chemical, kinetic, sound, heat, and potential energy. A battery is anything that has potential energy. Potential in a sense that it has possibility and capability of having the energy but it is not yet in existence. When you push a boulder on the top of the hill, the amount of energy you put into the boulder as you go up, is stored on potential energy, which then released when the boulder is rolling down the hill. This is a method to conserve energy to be used later. On the case of a household battery, chemical energy is stored and converted into electrical energy. In the case of electrochemical batteries this is done through connecting one or more galvanic cells.1.
3 Background Theory of a Battery:Fig 2. Conceptual Diagram of a “Galvanic Cell”Figure 2. Shows concept of a very simple battery; it is a very important basic knowledge to understand the chemistry of modern batteries. In any galvanic cell, one of reactant has to lose electrons; the lost electrons then gain by the other reactant. In the anode, the reactant that usually is a metal, undergoes oxidation, the electrons lost then travel through conductor to cathode, which then undergoes reduction.
In normal situation, we usually have load that is a device that needs to be powered placed in the middle.The process of losing electron is known as oxidation, this happens on the anode.Li (s) –> Li+ (aq)+ e- E0Oxidation = 3.03VThe process in which electrons are gained are called reduction it happens on the cathode.2H+(s) + 2e- –> H2 (aq) E0Reduction = 0.00VThese reactions are often referred as half equation, the full equation can be produced when the two half equations are combined. E0 refers to (Electromotive Force) or E.
M.F, this indicates the reactivity of the metals. With strongest reductant having the most negative value on the table and the strongest oxidant with the highest positive value.3 The amount of voltage and current a cell produces depends on the type of chemicals used to react with; while the endurance of a battery depends on the amount of active material within the battery and its actual design. The amount a cell gives out can be calculated by looking at their E.M.F. Table 1.
give you numerous E.M.F values of different compounds. Every compound has their own EMF, it is the tendency to gain or lose electrons, in relation with other compounds. The larger the difference will result a higher potential difference, and better battery.To demonstrate how to find the theoretical value of a galvanic cell, we can look at the chemical process in a Lithium battery. Lithium is a very promising material as it has high E.M.F value. Lithium batteries are small and light therefore they are only used when lightweight and small size is an important issue.Li (s) –> Li+ (aq)+ e- E0Oxidation = 3.03VH+(s) + e- –> 1/2 H2 (aq) E0Reduction = 0.00V +Li(s) + H+(s) –> Li+(s) + 1/2 H2 (g) E0 = 3.03V1.
4 Demonstration of Simple Galvanic cell:Aim/Purpose:To help illustrate a simple battery for readers.Figure 3.4 Diagram of Cu(s)/Cu2+(aq)||Zn2+(aq)/Zn(s)Result:The experiment was set up as Figure 3. for the material and method please refer to Appendix 1.1, and the E.M.F acquired from the experiment was 0.868V.Data Analysis:Electricity does exist within the battery; some of us may ask what actually happened during the experiment? What is oxidation and what is reduction? Why do they give out electricity? And how does it happen? So far we know that oxidation is a process of losing electrons, it happens in Anode. This is the reaction that happens in the anode side.Anode: Zn (s) –> Zn2+ (aq)+ 2e- 0.76VThe solid Zinc, has lost its electrons and become positively charged. The lost electrons then travel to the cathode side, in which reduction takes place. The electrons that travelled ended up joining the copper, and the load was powered in the process.Cathode: Cu2+(s) + 2e- –> Cu (aq) 0.34VZn (s) –> Zn2+ (aq)+ 2e- E0Oxidation = 0.76VCu2+(s) + 2e- –> Cu (aq)___ E0Reduction = 0.
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34V +Zn + Cu2+ –> Zn2+ + Cu2+(s) E0 = 1.1VThis experiment was done in S.T.P, all concentration used were 1M and the temperature was relatively closed to 25?C. The theoretical value can be found by adding the amount of E.M.F (Electromotive Force), which is the rate in which energy is drawn from a source that produces a flow of electricity in a circuit5. In theory the wet cell can give off 1.1V, (0.76V + 0.34V) but the procedure was not kept at high detail to get accuracy therefore energy are lost to environment and only 0.868V is detected. Which is around 78.9% of the theoretical value, some of the energy was probably lost into the environment during the process of oxidation, or probably the inaccuracy of the voltmeter used during the experiment may have affected the result.
P.T.OModern Battery / Dry CellFig 46.
Cutaway view of an alkaline battery.Figure 4. shows the new modern battery found in the supermarket nowadays. This type of cell is still based on the wet/ galvanic cell but it is far more complex in comparison to the wet cell discussed earlier. Most of us do not realise the fact that the outer casing of the battery is made by Zinc and is the anode of the battery. The pointy ends, is in-fact a graphite rod that act as the cathode surrounded by paste consisting manganese dioxide and ammonium chloride as well as zinc chloride, which act as the electrolyte.
On the outer casing of the battery the zinc undergoes oxidationZn(s) –> Zn2+(aq)+ 2e-On the cathode, the reaction is as follow:2MnO2 (s) + 2H+(aq) + 2e- –> Mn2O3 (s) + H2O (l)The 2H+(aq) needed in the reduction process is gained from the electrolyte within the paste, the reaction producing 2H+(aq) follows this reaction,NH+4 (aq) –> NH3 (aq) + H+(aq)There are three common dry-cell batteries, and they usually are classified by different electrolyte used in the battery. The battery mentioned at the top is mildly acidic dry-cell battery. In an acid based battery usually sulphuric acid (H2SO4) is used while in an alkaline battery the electrolyte is replaced with 7M KOH, alkaline batteries use powdered zinc anode is used to enhance reaction. Alkaline dry cell can last longer, however it does cost more than normal dry cells. Acid based battery is used in automobile batteries, but not in household battery as they are corrosive and seen as dangerous