Fuel, oxygen, and energy are the three things make up what is known as the fire triangle Figure 7 , and any one of them being absent means that combustion will not take place. In the modern world, many of the fuels that are typically burned for energy , are hydrocarbons — substances that contain both hydrogen and carbon as discussed in more detail in our Carbon Chemistry module.
Plants produce hydrocarbons when they grow, and thus make an excellent fuel source, and other hydrocarbons are produced when plants or animals decay over time such as natural gas , oil, and other substances. When these fuels combust, the hydrogen and carbon within them combine with oxygen to produce two very familiar compounds , water, and carbon dioxide. One simple example is the combustion of natural gas, or methane, CH 4 :.
As with the combustion of all fuels, heat and light are products , too, and it is these products that are used to cook our food or to heat our homes. Each of the four types of reaction above are sub-categories of a single type of chemical reaction known as redox reactions. A redox reaction is one where reduction and oxidation take place together, hence the name. The individual processes of oxidation and reduction can be defined in more than one way, but whatever the definition, the two processes are symbiotic, i.
In one definition, oxidation is described as the process in which a species loses electrons , and reduction is a process where a species gains electrons. In this way, we can see how the pair must take place together. If a chemical substance is to lose electrons and therefore be oxidized , then it must have another, interdependent chemical substance that it can give those electrons to.
In the process, the second substance the one gaining electrons is said to be reduced. Without such an electron acceptor, the original species can never lose the electrons and no oxidation can take place. When the electron acceptor is present, it gets reduced and the redox combination process is complete. Redox reactions of this type can be summarized by a pair of equations — one to show the loss of electrons the oxidation , and the other to show the gain of electrons the reduction.
Using the example of the Daniell cell above,. The electrons shown being lost by zinc in the first reaction , are the same electrons being accepted by the copper ions in the second. Together, the reactions can be combined to cancel out the electrons on either side of the reactions, into the overall redox reaction:.
Other definitions of oxidation and reduction also exist, but in every case, the two halves of the redox reaction remain symbiotic — one loses and the other gains. The loss from one species cannot happen without the other species gaining. Hard water causes all kinds of problems that go beyond just making it difficult to form a lather.
Textile manufacturing and the beverage industry rely heavily on water. In those situations, the quality of the water can make a difference to the end product , so controlling the water composition is crucial. Hard water contains magnesium or calcium ions in the form of a dissolved salt such as magnesium chloride or calcium chloride. A double displacement reaction also known as a double replacement reaction occurs when two ionic substances come together and both substances swap partners.
In general:. Where A and C are cations positively charged ions , and B and D are anions negatively charged. In the case of the reaction of soap with calcium chloride, the reaction is:. The solid calcium stearate is what we call soap scum, which is formed by the reaction of the soluble sodium stearate salt the soap in a double replacement reaction with calcium chloride.
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Acid-base reactions happen around, and even inside of us, all the time. From the classic elementary school baking soda volcano to the process of digestion, we encounter acids and bases on a daily basis.
Chemical Reactions (Essential Chemistry) | KSA | Souq
This hydrogen ion is the essential component of all acids , and indeed one definition of an acid is that of a hydrogen ion donor. Compounds such as the citric acid in lemon juice, the ethanoic acid in vinegar, or a typical laboratory acid like hydrochloric acid, all give their hydrogen ions away in chemical reactions known as acid-base reactions.
The chemical opposites of acids are known as bases , and bases can be defined as hydrogen ion acceptors. Whenever an acid donates a hydrogen ion to a base, an acid-base reaction has taken place, for example, when hydrochloric acid donates a hydrogen ion to a base such as sodium hydroxide:.
Equation 9c can be re-written to show the individual ions that are found in solution , thus:.
Chemistry Is Everywhere
Removing the spectator ions from the equation above, we get the net ionic equation:. Any chemical reaction that forms water from the reaction between an acid and base as in equation 9e is known as a neutralization reaction. The type of chemical reaction where a single constituent can substitute for another one already joined in a chemical compound is:. Chemical equations are always linked to chemical reactions since they are the shorthand by which chemical reactions are described.
Thousands of reactions are taking place all around you
That fact alone makes equations incredibly important, but equations also have a crucial role to play in describing the quantitative aspect of chemistry, something that we formally call stoichiometry. All chemical reactions take on the same, basic format.
The starting substances, or reactants , are listed using their chemical formula to the left-hand side of an arrow, with multiple reactants separated with plus signs. In the case of a reaction between carbon and oxygen:. To the right hand of the arrow one finds the chemical formulas of the new substance or substances known as the products that are produced by the chemical reaction.
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Order Form. As with molecular dissymmetry, Pasteur thus saw fermentation as a work of life that reinforced the hypothesis of an unknown original force, which specifically introduces these chemical properties into life forms. First, the discovery of enzymes explained, amongst other things, molecular dissymmetry and fermentation, paving the way for the chemistry of transformed living matter. He concluded:. This demonstrates that the fermentation process does not require so complicated an apparatus as is represented by the living cell.
I will come back to this point in more detail a bit later. This property, enzymatic catalysis, is certainly one of the great chemical secrets of life. On 25 April , an article in the famous scientific journal Nature described for the first time the structure of the DNA molecule deoxyribonucleic acid 9.
This discovery offered a brilliant illustration of the power of the reductionist approach which, in this precise case, went from the isolation of the biological molecule, by Friedrich Miescher in , to its chemical and structural characterization, which then provided the key to understanding its mechanism of physiological action. Once again I would like to stress how proud I, your colleague, am to be here, today. In my opinion, one of the great revelations of the analysis of the living world in the last forty years relates to the importance of the role played by metallic ions.
This is the domain that I have been continuously and passionately exploring with my laboratory for the past thirty years, and I would like to convince you of the importance of this science, in a few words. French biochemist Gabriel Bertrand , who was Chair of Biological Chemistry at the Sorbonne in , was one of the first to suggest that metal could act as a catalyst in enzymes, after studying the oxidation reactions catalyzed by a copper enzyme, laccase. It was first in the years from to , with a Russian chemist named David Keilin , and then in the mids with Helmut Beinert , a German physicist who emigrated to the United States during the Second World War and recently passed away, that we understood that the complex chemistry of breathing depends on metalloenzymatic systems like cytochrome oxidase, which contains iron and copper.
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We have been working on the latter components for many years in my laboratory and are still very actively doing so. The syntheses that led to the first elaborate molecules of life presumably occurred on the reactive surface of solid metallic sulphurs, iron and nickel. Between this genesis, several billion years ago, and now, nothing has changed: almost all the major functions of life are carried out by metalloproteins and metalloenzymes, therefore requiring the presence of one or several sodium, calcium, zinc, iron or copper atoms.
Without magnesium, calcium and manganese, which constitute the crucial elements of plant and algae photosynthesis, there would be neither oxygen nor the organic matter which provides us with energy. And it is thanks to the iron and copper in our oxidases that, through breathing, we are able to use this resource to our own benefit, while also giving back to nature the carbon dioxide it needs.