Acids, Bases and Salts

Acids

Acids are known for being corrosive and sour but in truth acids are defined due to their tendency for relieving hydrogen ions in an aqueous solution. There are two types of acids, organic acids and inorganic/ mineral acids. Organic acids are found in plants and animals and are helpful rather than being harmful in most cases. Organ acids are more commonly found in the fruits we eat. The inorganic acids or mineral acids are found in Labs throughout the world, one example is the sulfuric acid.

These types of acids are more commonly known due to the properties, which are, turning blue litmus paper red, having a sour taste and being corrosive. These acids are used either in dilute form or concentrated form but in either case safety is necessary which can be ensured by wearing gloves and eye protection. When carrying bottles of corrosive acid, make sure to place it on a tray so that it does not damage the surface of the table or floor or whichever surface it is placed in.

All acids have almost the same structure and the same chemistry. The acids are determined to be either strong or weak by observing the amount of hydrogen ions they release in aqueous solution, such as a hydrochloric acid solution is mixed in water and is completely ionised, indicating it is a strong acid; HCL + H2O → H+ + Cl-, in case of acids like ethanoic acid, the acid is not completely ionised and so, is a weak acid but since it is a reversible reaction, the sign “↔” shows that the reaction is not complete and also indicates that the reaction is continuously using and discharging the hydrogen ions: CH3COOH + H2O ↔ CH3COO- + H+.

The same situation is used to determine the basicity of an acid. Such as HCL only releases 1 hydrogen ion per reaction thus is a monobasic acid, Sulfuric Acid releases 2 hydrogen ions per reaction and so is a dibasic acid, a phosphoric acid is a tribasic acid which releases 3 hydrogen ions.

Acids react with metals to release salt and hydrogen gas, they react with metal carbonate and hydrogen carbonates to release carbon dioxide, the acids also react with bases to form salt and water.

Bases

Bases are all those chemicals which release hydroxide ions and oxide ions. The bases also react with acid to form salts and water. These type of reactions are more commonly known as neutralization reactions because the resulting products water and salts are neutral, neither acid nor basic, with a pH of 7. Bases are mostly metal oxides and metal hydroxides which do not dissolve in water but there are bases in Group I and some in Group II of the periodic table, including ammonia, which dissolve in water. These bases are known as Alkalis.

Acids, Bases and Amphoteric oxides 

Acid oxides are those oxides which dissolve in water to form acids. Base oxides are those metal hydroxides or oxides which react with acids to form salt and water, but in cases of Group I and Group II Bases we can say that these metal hydroxides and oxides react with water to form an alkaline solution. The Amphoteric oxides are those base oxides which react with acids to form salt and water but also act as an acid and react with other bases to form salt and water as well.

Preparing Salts

Salts are neutral compounds (in most cases) formed when acids react with bases. Salts are formed when the hydrogen ions in an acid is completely replaced with metal. In some acid-metal reactions, metals do not replace the hydrogen ions completely because the compound is likely to have more hydrogen ions than 1, therefore the salt formed will be called an acid salt.

Salts can be prepared, by reacting acids with metals, which are above hydrogen in the reactivity series, or by reacting acids with metal carbonates or even reacting acids with bases. In any case the most affective way of carrying out the reactions is by the use of titration method. This method involves the apparatus; a conical flask and a burette. The burette is filled with an acid while the conical flask is placed underneath it with a base, there is an indicator mixed in it. The acid is poured to the point where the color of the mixture changes, the mixture is stirred along the reaction. When this happens the initial chemicals are again used according to the new measurements and then the mixture is heated and then set to cool and crystallize. This is done because the last mixture has an indicator in it which makes it useless because the salt is needed in pure form.

Universal Indicators and the pH scale

To detect whether a solution is acidic or basic we use various indicators to show us this. There are many indicators used across the globe, most common one is the litmus paper which may be in red or blue and change into latter when placed in an acidic or alkaline solution. But such indicators are not useful if we were to detect the exact amount of acidity or basicity of the solution. For such reasons we use the universal indicator which has many indicators joined up to form one whole scale which can detect various ranges of acidity and basicity. The pH scale is used to number the amount of acidity and basicity of a solution. The pH scale was introduced by the Danish chemist SP S∅rensen in 1909. The pH is the abbreviation for “potential for hydrogen”. The pH has a range of 0 to 14 and being a logarithmic scale, each range is 10 times greater than the last, meaning an acid with a pH of 3 is 10 times more acidic than the acid having a pH of 4. The pH 7 is supposedly neutral solution.