Discuss the difference between acids, alkalis, and bases. Discuss and compare the reactivity of alkali metals with those of alkali earths. 

Expert Answers

An illustration of the letter 'A' in a speech bubbles

Differences between acids, alkali, and bases:

  • Acids are chemicals that have a pH of less than 7.0, while bases are substances that have a pH of more than 7.0.
  • Acids can also be thought of as chemicals that donate protons, while bases are chemicals that accept protons.
  • An...

Unlock
This Answer Now

Start your 48-hour free trial to unlock this answer and thousands more. Enjoy eNotes ad-free and cancel anytime.

Start your 48-Hour Free Trial

Differences between acids, alkali, and bases:

  • Acids are chemicals that have a pH of less than 7.0, while bases are substances that have a pH of more than 7.0.
  • Acids can also be thought of as chemicals that donate protons, while bases are chemicals that accept protons.
  • An acid can also be thought of as a chemical that can neutralize a base. Similarly, a base can neutralize an acid.
  • Acids turn litmus paper red, while bases make litmus paper turn blue.
  • Some examples of acids are sulfuric acid, hydrochloric acid, nitric acid, and so on. Some examples of bases are sodium hydroxide, potassium hydroxide, and so on.
  • Acids generally taste sour, while bases have a bitter taste.

Alkalis are the bases that are water-soluble, which means that they dissolve in water. In other words, not all bases are water-soluble, and only the water-soluble bases are known as alkalis. An example of an alkali is sodium hydroxide. It is a base because it can neutralize an acid, and because it is water-soluble, it is an alkali. An example of a base that is not alkali is copper oxide. This chemical can neutralize an acid, but it is insoluble in water.

In other words, all alkali are bases but not all bases are alkalis.

Also, an alkali has a hydroxide group, while a base has an oxide group in it.


Reactivity of Alkali metals with Alkaline Earth m
etals:

Alkali metals are group I (or group IA) elements in a periodic table of elements. These include metals such as sodium, lithium, potassium, and so on. Alkaline earth metals are group II (or group IIA) elements and include metals such as calcium, magnesium, barium, and so on. Both the alkali and alkaline earth metals are very reactive due to the loosely associated valence electrons.

In case of alkali metals, only one electron is present in the outermost shell. It is easier to lose this electron to attain a filled electronic configuration. In case of an alkaline earth metal, there are two valence electrons. Since two electrons are a little more difficult to lose when compared to one electron, alkaline earth metals are less reactive when compared to the alkali metals. For example, it is easier for a sodium atom to lose one electron than it is for a magnesium atom to lose two electrons. This means that sodium is more reactive when compared to magnesium.

If we go down a group in the periodic table, the reactivity increases. This is mostly due to an increase in the size of atoms, which results in less nuclear attraction for the valence electrons. This makes the electrons easier to lose, which results in an increase in the reactivity of the atom.

Hope this helps.

Approved by eNotes Editorial Team