Table of Contents
By definition, an acid can be defined as any substance which when added to water, the concentration of the hydrogen ions (H+) increases. This is the Arrhenius definition of an acid. There are two categories of acids, weak acids and strong acids. Acids which fully ionize in water are known as strong acid and on the contrary, acids which partially ionize in water are known as weak acids. The strength of an acid is measured by use of a scale known as ph scale. Acids fall in the range of 1 to 7 on the ph scale. To determine the presence of an acid, an indicator is used or alternatively, the litmus paper is used to determine if an acid is present whereby an acid changes a blue litmus paper to red and has no effect on a red litmus paper. When an acid is dissolved into water, hydrogen ions are formed as shown this equation and as a result, there is formation of acidic solution.
The quantity of the concentration of H+ greatly dictates if the acid is strong or weak. If a solution has a high concentration of hydrogen ions, it has the properties of a strong acid and the contrary is true for a weak acid.
Acids have the following characteristics. All acids conduct electricity. This is because of the presence of hydrogen ions, H+ which facilitates conveyance of electric currents. Also, all acids have a tart tang. This can be illustrated using vinegar which is a type of an acid.
Neutralization reaction occurs when acids are added to bases. This is facilitated by the reaction of hydroxide ions in the base and the hydrogen ions in the acid and as a result, only two products are formed: salt and water. For instance when HCl reacts with NaOH, there is production of NaCl and H2O as illustrated by the equation below
NaOH + HCl NaCl + H2O
Base +Acid Salt +Water
Reaction between acids and metals yields the metal’s corresponding salt and hydrogen gas. In this reaction, there is Redox reaction in which the H+ is oxidized while at the same time the metal is reduced resulting into the products of hydrogen gas and metal salt. The equation below shows reaction that occurs between zinc and HCl producing H2 and ZnCl2
Zn + 2HCl H2 + ZnCl2
Salt, carbon IV oxide and water are liberated in a reaction between an acid and carbonates. The equation written below show a reaction between HCl (an acid) and NaCO3 (a carbonate) to produce water, sodium chloride and CO2
In real life applications acids are found in human stomach to aid in digestion of food and to kill disease causing micro-organisms.
In crop production, acids play an important role in the neutralization of the soil in case of excessive bases. Crops thrive well in a soil ph of approximately seven. To enhance this, calcium, oxide is most commonly used in the neutralization process. When stung with wasps, an acid (vinegar is most commonly used) is the best remedy to relieve the pain produced by the sting. This is because the wasp’s sting is basic in nature and therefore to neutralize this effect an acid has to be used to neutralize the base.
On the contrary a base is defined as a compound which after addition to water, there is an increase in the concentration of hydroxide ions, OH- . Examples of bases entail all metal hydroxides and metal oxides. This includes all metal oxides, all metal hydroxides, ammonia among others. Bases are categorized into two categories: Base which dissolve in water (which are called Alkali) and insoluble bases. When a base is dissolved in water, hydroxide ions forms in a process know as ionization. This is illustrated in this equation which shows ionization of bases.
NaOH Na+ + OH-
There are two categories of bases: Strong bases and weak bases. This strength is determined by the easiness with which the base ionizes in water. The easier it dissolves in water the stronger the base and the contrary is true for weak bases. Like acids, the strength of acids is measured using the ph scale. The scale of bases ranges from seven to fourteen with weak acids ranging from seven to nine and strong bases ranging from ten to fourteen on the ph scale. The presence of a base is determined by use of indicators as well as a litmus paper. To test for a base using a litmus paper, a blue litmus paper is added in the base and this changes the color of litmus paper from red to blue indicating presence of a base. The presence of hydroxide ions in bases makes them to be goo conductors of electric current. Moreover bases have neutralized acids, have a bitter taste and feel soapy. Because of the active hydroxide ions, bases are corrosive in nature corroding both organic and inorganic substances.
The reaction of bases with different elements varies tremendously. Reaction between a base and acid produces of water and a corresponding salt. To illustrate this, the equation below shows the reaction between aqueous hydrochloric acid which is an acid and sodium hydroxide which is a base and the final products are sodium chloride which is a salt and water.
NaOH (aq)+HCl (aq) NaCl (aq)+H2O
In their application in chemistry and real life, bases are used as catalysts in a wide range of chemical reactions. These bases that can be used as catalysts include magnesium oxide, calcium oxide, barium oxide and zeolites. In the manufacture of toothpastes, bases are employed since they destroy the niche of the diseases causing micro –organisms. The commonly used base in this making of tooth past is sodium fluoride. Therefore, bases ensures every person who uses toothpaste has health teeth
Finally, buffers are other important compounds in chemistry. Buffers can be defined as a compound which possesses both basic and acidic properties. Buffers exist in two categories: acidic and basic buffers. Buffers have a resistance to ph change. This implies that on addition of a basic solution or an acidic solution, the change in ph is insignificance. Therefore, it is evident that a buffer consists of weak acids together with its corresponding weak conjugate base. When an acid (hydrogen ions) are added to a buffer, the weak base in the buffer resists ph change and therefore there is insignificance change in the ph properties of the resulting solution. Like wise, when hydroxide ions ((OH-) – which represents a base – are added to a base, the weak acid resists the ph change and therefore there is very little or no change in the ph properties of the resulting compound. A compound made of a mixture of acetic acid and sodium acetate is an example of a buffer compound. In this compound, the strong base has been turned into a weak base (CH3COO). The presence of this base has very little effect or insignificance on the acidic or basic properties of the resultant solution. For instance, addition oh hydrochloric acid to this buffer solution, there is combination to form a very weak acid that has no effect on the acidity or basic nature of the resultant solution. This has been illustrated by the equation below.
CH3COO- + H + CH3COOH
Conversely, Addition of a strong base for instance sodium hydroxide combines with the buffer and produces a weak base which has insignificant effect on the ph. This is illustrated in the equation below.
CH3COOH + OH- CHCOO-+ H2O
Mixture of carbonic acid (H2CO3) and its conjugate base which is bicarbonate ion (HCO3 -) is the most widely used buffer system in the body
Buffer solutions are very important and as a result have wide applications both in the human body and industrially. The human body utilizes buffers to keep the blood ph maintained between 7.35 – 7.45 and in a large number of enzymatic reactions This is because all the biological processes needs a ph of around 7 to efficiently occur. Extreme ph solutions will denature the enzymes thus the biological processes will not occur. Furthermore, the ph of the blood has to be restricted from going to the extreme values. This is because the production of Carbon IV oxide greatly influences the ph of the blood. This can be illustrated in the equation below:
H2O + CO2 H+ +HCO3-
Therefore, the presence of buffers is essential to make sure the blood is maintained at the correct ph. As shown in the equation below and this keeps the Ph maintained to normal.
H+ +HCO3- H2CO3
For chemists or biologists performing laboratory experiments, a ph of a given value will be required to facilitate the process being studied to occur and this is achieved through use of buffers. Other uses of buffers include its use in shampoos to prevent irritation by counteracting the basic effect of soaps, Used in baby lotions, eye drops, washing powders among other uses.
Acids, buffers and bases are very vital in human life. These compounds facilitate a wide range of process to occur in all fields of life. Hence this signifies the importance of this study.