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Difference between Alkalis and Bases

  • Last Updated : 07 Dec, 2021

An alkali is a basic ionic salt of an alkali metal or an alkaline earth element in chemistry. A base that dissolves in water is also known as an alkali. The pH of a soluble base solution is more than 7.0. In English, the adjectives alkaline and alkalescent are frequently used as synonyms for basic, especially for bases soluble in water. Because alkalis were the first bases found to obey the Arrhenius definition of a base, and they are still among the most frequent bases, this broad usage of the term is likely to have arisen.

What are Bases?

A base is a material that is used to neutralise the acid. Metal hydroxides and metal oxides are examples of bases that react with acids to produce a neutral result.

Water does not dissolve bases. Zinc hydroxide and copper oxide are examples of bases. Following are some important properties of bases: 

  • The base interacts with the acid to neutralise it.
  • The base has a harsh flavour and is slick to the touch.
  • When they react with acids, they form salt molecules and water.
  • A strong base and a weak base are two different types of bases.
    • NaOH is an example of a strong base.
    • NH3 is an example of a weak base.

Alkalis

Alkalies are chemical groups with a high pH. These compounds are essentially ubiquitous, and they have a wide range of uses in biological and industrial systems. 

Aluminium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, and lithium carbonate are some of the most regularly utilised alkalies that can cause toxicity. Ammonium hydroxide and lithium carbonate are two alkalies that are commonly utilised to treat a wide range of illnesses and disorders. In clinical medicine, bicarbonate-containing alkalies are widely used to treat metabolic acidosis. 

Alkaline biological fluids (blood, serum, urine, saliva, vaginal secretions) and soil have a pH of 7.4 or above. However, there aren’t many cases of fatalities caused by alkalis.

Dissociation of Alkalis

An alkali, on the other hand, dissociates to liberate OH ions. Any free H+ ions in the solution bond to these OH ions (forming water or H2O). As a result, the amount of free H+ ions decreases and the pH rises. As a result, alkalis are sometimes referred to as H+ ion acceptors.

CHNaO3, often known as baking soda or bicarbonate of soda, is a weak alkali. It does not release many of its OH ions when it dissociates in water. A strong alkali, such as NaOH (sodium hydroxide or caustic soda), on the other hand, releases practically all of its OH ions in solution.

A considerable number of free OH ions are present in alkaline solutions. These OH ions like to bond to any free H+ ions they come across. Because pH counts the quantity of free H+ ions, this increases the pH number or value of an alkaline solution.

The most important thing to remember about alkalis is that they are all bases, but not all bases are alkalis.

Acids are neutralised by bases, which constitute a group of medications. Alkalis are water-soluble bases. They require a slick, soapy sensation, as well as pH values greater than 7. Caustic soda, milk of magnesia, sodium bicarbonate (sodium bicarbonate), hypochlorite, and ammonia are all common examples.

Paper, detergents, and soap are all made with sodium hydroxide. Potash is used by farmers to make acidic soil more alkaline so that plants may grow better in it, and it is also used as an electrolyte in alkaline, Ni-Cd, and Ni-MH batteries.

Difference between Alkali and Base

Base

Alkali

When dissolved in water, the base will increase the concentration of OH-ions. When an alkali is dissolved in water, the resultant solution is clear. The solution may also have an unpleasant odour. However, the amount of water, alkali, and pH value of the alkali all have a role.
When you taste bases, they are harsh. The remainder, with the exception of ammonia, is odourless. They’re slick, and they react to fats and oils.The physical and chemical properties of alkali are the same. They’re soft and cut easily with a knife. Their melting points are low, and their densities are low. Sodium, potassium, and lithium, for example, are too heavy to float in water.
Bases have a harsh flavour and a slick, soap-like texture. They create water and salt molecules when they react with acids. Alkalis are chemicals that are used to soften water and remove organic tannins, fluorides, and other contaminants. They’re utilised to bring water’s pH levels back to normal. Alkali is used to keep sewage sludge clean and decrease odour.
When bases react with water, they dissociate, releasing a free hydrogen ion (OH-). Alkalis, on the other hand, react aggressively when coupled with water. The reaction yields hydrogen gas and base, a very alkaline solution.

They are used to aid increase visibility in industrial applications and mining activities. This also aids in the elimination of phosphate and nitrogen. Sodium chloride, an alkali, is used as table salt in kitchens. Gastric medication, soaps, detergents, and cleansers all employ bases.

They’re also utilised to neutralise acidic wastewater as a non-hazardous alkali. They’re also found in antiperspirant armpit deodorants.

 The most common bases are ammonia, baking soda, and caustic soda.Alkalis are lustrous, soft metals with silvery tint. One electron covers its exterior shell. They create +1 cations when they are eliminated.

Sample Questions

Question 1: Why does lemon juice have a sour taste?

Answer:

Lemon juice has a sour taste because it contains H+ ions that give a sour taste.

Question 2: Agricultural lime is used in acidic fields. Why?

Answer:

They are used in acidic fields because lime is basic in nature that reacts with acidic soil and the acidity of the soil is reduced.

Question 3: Hydrochloric acid is known as a strong acid. How?

Answer:

Hydrochloric acid is known as a  strong acid because it undergoes almost complete ionization and gives a high concentration of hydrogen ions.

Question 4: Acids can be said as proton donors. Justify?

Answer:

It gives hydrogen ions when dissolve in water so, it can be said as proton donors.

Question 5: Copper sulphate solution shows acidic nature. Why?

Answer:

Copper sulphate is a salt that is formed from the reaction of a weak base and strong acid. Thus, it is an acidic salt and shows acidic nature.

Question 6. “All alkalis are bases but all bases are not alkalis”. Justify?

Answer:

Some bases are soluble in water and others are insoluble in water. Water soluble bases are called alkalis while bases, which are not soluble in water, are not alkalis. Therefore, all alkalis are bases but all bases are not alkalis.

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