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Chemical Engineering Basics - Engineering

Q1:

Pick out the correct statement.

A A base is always soluble in water.

B Hydrogen is released whenever a metal reacts with an acid.

C Sodium hydroxide is both a base and an alkali.

D All indicators give red solution with an acid.

ANS:C - Sodium hydroxide is both a base and an alkali.

Sodium hydroxide (NaOH) is both a base and an alkali due to its chemical properties and behavior in aqueous solutions. As a base:

  • Sodium hydroxide is a strong base because it readily donates hydroxide ions (OH-) in solution.
  • It reacts with acids to form salts and water through a neutralization reaction. In this reaction, sodium hydroxide accepts a proton (H+) from the acid, forming water (H2O) and a salt.
As an alkali:
  • An alkali is a soluble base that produces hydroxide ions (OH-) when dissolved in water.
  • Sodium hydroxide readily dissociates in water to produce hydroxide ions, making it an alkali.
  • Alkalis have a bitter taste, feel slippery or soapy to the touch, and turn red litmus paper blue. Sodium hydroxide exhibits these characteristics when dissolved in water.
Therefore, sodium hydroxide is classified as both a base and an alkali due to its ability to donate hydroxide ions and its behavior in aqueous solutions.