What is a concentrated base?

• A. A base that contains a large number of OH- hydroxide ions.
• B. A base that contains a small number of OH- hydroxide ions.
• C. A base that does not ionise in solution.
• D. A base that forms water when dissolved.

Answer: (A)

A concentrated base is one that provides a large amount of hydroxide ions in solution. In water, bases increase the concentration of OH− ions, and “concentrated” means this occurs at a high level—many OH− ions per liter. That’s why concentrated bases have a stronger basic effect and a higher pH than the same base in dilute solution. Remember, concentration (how much solute is in a given volume) is different from strength (how completely the base dissociates). A base can be strong or weak regardless of whether it is concentrated or dilute.