Properties of Base
- The base is generally bitter.
- Under normal conditions, the pH of basic solutions is always greater than 7.
- Concentrated solutions of relatively strong bases (such as concentrated sodium hydroxide) are known to react violently with acidic substances. Therefore, such substances should be stored with care.
- Strong bases are also known to corrode organic materials. Great care must be taken when handling such materials as accidental spills on the skin can cause severe burns and permanent tissue damage.
- All pure substances have similar effects on certain chemical indicators. For example, all bases have the ability to turn red and litmus blue. It is also known to make methyl orange yellow and phenolphthalein pink.
- In the molten or aqueous state, bases are excellent electrical conductors (because they dissociate into ions and increase the conductivity of the material).
The reaction of the base with Metals:
- When a base reacts with metals, salt formation occurs with the release of hydrogen gas.
- The equation can be written in words as:
Metal + Base → Salt + Hydrogen↑
If sodium hydroxide (NaOH) reacts with zinc (Zn), sodium zincate is formed with the liberation of hydrogen gas (H2).
Zn (s) + 2 NaOH (aq) → Na2ZnO2 (aq) + H2 (g)
What happens when a base reacts with a metal?
When a base reacts with a metal, salt and hydrogen gas are released. The base turns the litmus paper which is red in color to blue. The word equation of this reaction is Metal + Base → Salt + Hydrogen↑