To determine which of the following substances is a strong base, let’s analyze each one in detail:
1. CH₃OH (Methanol): Methanol is an alcohol. Alcohols generally do not dissociate in water to release hydroxide ions (OH⁻), which is a characteristic of a base. Thus, methanol is neither a strong base nor a base at all.
2. CH₃COOH (Acetic Acid): Acetic acid is a well-known weak acid. It only partially dissociates in water to release hydrogen ions (H⁺). Since it is an acid, it definitely cannot be a strong base.
3. NH₃ (Ammonia): Ammonia is indeed a base, but it is classified as a weak base. In aqueous solution, ammonia only partially accepts protons (H⁺) and releases hydroxide ions (OH⁻). However, as it does not fully dissociate in solution, it doesn’t qualify as a strong base.
4. Ba(OH)₂ (Barium hydroxide): Barium hydroxide is one of the classic examples of a strong base. In water, Ba(OH)₂ fully dissociates into barium ions (Ba²⁺) and hydroxide ions (OH⁻). This complete dissociation is a defining characteristic of strong bases.
The correct answer is Ba(OH)₂ (Barium hydroxide) since it is the only substance among the given options that fully dissociates in water to produce a high concentration of hydroxide ions, qualifying it as a strong base.
